Selective, Nickel-Catalyzed Hydrogenolysis of Aryl Ethers · Selective, Nickel-Catalyzed Hydrogenolysis of Aryl Ethers. Supporting Online Material. 4 a final temperature of 300 °C,

www.sciencemag.org/cgi/content/full/332/6028/439/DC1

Supporting Online Material for

Selective, Nickel-Catalyzed Hydrogenolysis of Aryl Ethers

Alexey G. Sergeev and John F. Hartwig*

*To whom correspondence should be addressed. E-mail: [email protected]

Published 22 April 2011, Science 332, 439 (2010)

DOI: 10.1126/science.1200437

This PDF file includes:

Materials and Methods

SOM Text

Figs. S1 to S3

Tables S1 to S6

References

Supporting Online Material

Selective, Nickel-Catalyzed Hydrogenolysis of Aryl Ethers Alexey G. Sergeev and John F. Hartwig*

Department of Chemistry, University of Illinois, 600 South Matthews Avenue, Urbana, Illinois 61801

Table of Contents:

1. Full References from the Main Text 3

2. General Experimental Details 3

3. Preparation of Aryl and Benzyl Ethers 5

4. Stability of the Ni(COD)2/PCy3 Catalyst Under the Conditions of Reductive

Cleavage of Aromatic C-O bonds 15

Figure S1. Attempted Hydrogenolysis of Diphenyl Ether Catalyzed

by Ni(COD)2/PCy3 15

Figure S2. Attempted Reductive Cleavage of Anisole with Triethylsilane

Catalyzed by Ni(COD)2/PCy3 16

5. Nickel-NHC Catalyzed Reductive Cleavage of Aryl and Benzyl Ethers with

Hydride Donors 18

Discussion 19

Table S1. Selected Results on the Effect of Ligand, Nickel and Hydride

Source and Base Amount on the Reductive Cleavage of Diphenyl Ether 21

Figure S3. Carbene Ligands Used in the Study 21

Table S2. Reductive Cleavage of Aryl and Benzyl Ethers with Hydride Donors 22

6. Nickel-NHC Catalyzed Selective Hydrogenolysis of Aryl and Benzyl Ethers 29

Competition Experiments 43

*To whom correspondence should be addressed. E-mail: [email protected]

Selective, Nickel-Catalyzed Hydrogenolysis of Aryl Ethers. Supporting Online Material.

2

Mercury Poisioning Experiments 45

Table S3. Selected Results on Effect of Ligand, Temperature and

Amount of Base on Hydrogenolysis of Diphenyl Ether 47

Table S4. Effect of Ligand, Nickel Source, Temperature, Amount of Base and

AlMe3 on Hydrogenolysis of 2-Methoxynaphthalene 47

Table S5. Control Experiments for Hydrogenolyisis of 2-Methoxynaphthalene 48

Table S6. Catalyst Stability Estimation in Hydrogenolysis of Methyl Aryl Ethers 48

7. NMR spectra 49

8. References 67


3

1. Full References from the Main Text

Ref. 20: B. T. Guan, S. K. Xiang, T. Wu, Z. P. Sun, B. Q. Wang, K. Q. Zhao, Z. J. Shi,

Chem. Comm., 1437 (2008).

Ref. 35: B. A. Ellsworth, W. Meng, M. Patel, R. N. Girotra, G. Wu, P. M. Sher, D. L.

Hagan, M. T. Obermeier, W. G. Humphreys, J. G. Robertson, A.Wang, S. Han, T.

L.Waldron, N. N. Morgan, J. M. Whaley, W. N. Washburn, Bioorg. Med. Chem. Lett. 18,

4770 (2008).

2. General Experimental Details

Equipment and methods

All air-sensitive manipulations were conducted under an inert atmosphere in a nitrogen-

filled Innovative Technology glovebox or by standard Schlenk technique under argon.

All glassware was heated in an oven and cooled in an inert atmosphere prior to use.

GC analyses were obtained on an Agilent 6890 Gas Chromatograph equipped with an HP-

5 25 m x 0.20 mm ID x 0.33 µm capillary column (Agilent) and an FID detector.

The following GC oven temperature programs were used: A) 100 °C hold for 3 min,

ramp 40 °C/min to a final temperature of 300 °C, and hold for 2.5 min; B) 80 °C, ramp

110 °C/min to a final temperature of 300 °C, and hold for 3.2 min; C) 35 °C hold for 2

min, ramp 45 °C/min to a final temperature of 300 °C, and hold for 2 min. Helium was

used as a carrier gas, with a constant column flow of 5.6 ml/min (program A and B) or

6.6 ml/min (program C). The injector temperature was held at 250 °C (program A) or 300

°C (program B and C).

GC-MS analyses were obtained on an Agilent 6890-N Gas Chromatograph equipped with

an HP-5 30 m × 0.25 mm × 0.25 µm capillary column (Agilent). The GC was directly

interfaced to an Agilent 5973 mass selective detector (EI, 70 eV). The following GC oven

temperature programs were used: A) 50 °C hold for 2 min, ramp 40 °C/min to a final

temperature of 300 °C, and hold for 2 min; B) 100 °C hold for 3 min, ramp 40 °C/min to


4

a final temperature of 300 °C, and hold for 2.5 min. Helium was used as a carrier gas,

with a constant column flow of 1 ml/min. The injector temperature was held constant at

250 °C.

NMR spectra were acquired on a 400 MHz Varian Unity instrument or on 500 MHz

Varian Unity or Inova instruments at the University of Illinois VOICE NMR facility.

Chemical shifts are reported in ppm relative to a peak of a residual protiated solvent

(CDCl3, δ 7.26 ppm for 1H and 77 ppm for 13C).

Flash column chromatography was performed on a Teledyne Isco CombiFlash Rf

automated chromatography system with RediSep Rf Gold normal-phase silica columns (40

and 80 g).

Analytical thin-layer chromatography (TLC) was performed using glass plates pre-coated

with silica gel (0.25 mm, 60 Å pore size) impregnated with a fluorescent indicator (254

nm). TLC plates were visualized by exposure to ultraviolet light (UV) and/or submersion

in aqueous potassium permanganate solution (KMnO4), followed by brief heating.

Elemental analyses were performed by the University of Illinois at Urbana-Champaign

Microanalysis Laboratory and by Robertson Microlit Laboratories, Inc. (Madison, NJ).

Solvents and reagents

Benzene, toluene, and tetrahydrofuran (THF) were degassed by purging with nitrogen for

45 min and purified using an Innovative Technology Pure Solv PS-400-6 solvent

purification system equipped with 1 m column with activated alumina. Anhydrous

dioxane, m-xylene and dimethylsulfoxide (DMSO) where purchased from Aldrich and

used as received. All the solvents were stored under nitrogen atmosphere in glovebox.

Methylene chloride, diethyl ether, acetone, ethyl acetate and hexanes were purchased

from Fisher Scientific and used as received. Nickel acetylacetonate (Ni(acac)2) and nickel

cyclooctadiene (Ni(COD)2) were purchased from Aldrich or Aldrich and Strem

respectively. Tricyclohexylphosphine was purchased from Strem. 1,3-Bis(2,6-di-iso-

propylphenyl)imidazolinium tetrafluoroborate (SIPr·HBF4) was purchased from Aldrich,

1,3-Bis(2,6-di-isopropylphenyl)imidazolinium chloride (SIPr·HCl) (S1) and 4,5-dimethyl-


5

1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (IPrMe·HCl) (S2) were prepared

according to the literature procedures. m-Bis(m-phenoxyphenyl)benzene (Santovac© 5P

Ultra) was purchased from Scientific Instrument Services, Inc. 4-methoxybiphenyl, and

phenyl 4-trifluoromethylphenyl ether were purchased from Alfa-Aesar. Diphenyl ether,

di-4-methylphenyl ether, 4-tert-butylanisole, anisole, dibenzofuran, 1- and 2-

methoxynaphthalene, sodium tert-butoxide were purchased from Aldrich and used as

received. Triethylsilane, diisobutylaluminum hydride (1M solution in hexanes),

trimethylaluminum (2M solution in toluene) were purchased from Aldrich. N-methy-N-

(trimethylsilyl) trifluoroacetamide (MSTFA) was ordered from Acros. Anhydrous copper

iodide, pyridine-2-carboxylic acid (picolinic acid), anhydrous K3PO4, phenols and aryl

iodides (if not otherwise mentioned) were purchased from Aldrich. Other solvents and

reagents were ordered from Aldrich and used as received. Hydrogen (>99%) was

purchased from Linde Gas North America LLC and used as received.

3. Preparation of Diaryl and Benzyl Ethers General procedure for the preparation of diarylethers (modified literature

procedure) (S3)

O

R1 R2

HO

R1 R2

+I

K3PO4, DMSO,100 oC, 20h

10 mol% CuI,20 mol% L

N CO2HL =

In a glovebox, a 50 ml round bottom flask was charged with copper (I) iodide (152 mg,

0.798 mmol), picolinic acid (pyridine-2-carboxylic acid, 197 mg, 1.60 mmol), aryl iodide

(8.00 mmol), phenol (9.60 mmol), potassium phosphate (16.0 mmol, 3.40 g), a magnetic

stir bar and DMSO (16 ml). The reaction flask was sealed with a septum, removed from

the box, and the reaction mixture was stirred at 100 °C for 20 h. The reaction mixture was

cooled and diluted with a 1:1 mixture of saturated aqueous solution of ammonium

chloride (100 ml) and water (100 ml). The crude product was extracted with methylene

chloride (3×100 ml). The combined organic extracts were successively washed with a 5%

aqueous solution of potassium hydroxide (100 ml), brine (100 ml) and dried over


6

anhydrous sodium sulfate. The crude product was preadsorbed on silicagel (3-4 g) and

purified by flash column chromatography.

Di-2-methoxyphenyl ether (a model of the 5-O-5 lignin ether linkage) (S4)

Prepared according to the general procedure using 2-iodoanisole (0.963 g,

4.11 mmol), guaiacol (2-methoxyphenol, 0.597 g, 4.81 mmol), potassium

phosphate (1.89 g, 8.90 mmol), copper (I) iodide (78 mg, 0.41 mmol), pyridine-2-

carboxylic acid (100 mg, 0.812 mmol) and DMSO (8 ml). The crude product was

purified by flash column chromatography (eluent: hexanes to hexanes-ethyl acetate, 10:1)

to give di-2-methoxyphenyl ether as a white solid (0.425 g, 1.84 mmol) in 45% yield. 1H

NMR (400 MHz, CDCl3) δ 7.04-7.10 (m, 2H), 6.98 (dd, J = 1.5, 8.0 Hz, 2H), 6.80-6.90

(m, 4H), 3.86 (s, 6H). 13C {1H} NMR (100 MHz, CDCl3) δ 150.5 (C), 146.0 (C), 123.7

(CH), 120.8 (CH), 118.8 (CH), 112.6 (CH), 55.9 (CH3).

2-Methoxyphenyl phenyl ether (a model of the 5-O-5 lignin ether linkage) (S5)

Prepared according to the general procedure using iodobenzene (0.760 g,

3.16 mmol), guaiacol (2-methoxyphenol, 0.654 g, 5.26 mmol), potassium

phosphate (1.78 g, 8.34 mmol), copper (I) iodide (80 mg, 0.42 mmol),

pyridine-2-carboxylic acid (103 mg, 0.836 mmol) and DMSO (8 ml). The crude product

was purified by flash column chromatography (eluent: hexanes to hexanes-ethyl acetate,

10:1) to give 2-methoxyphenyl phenyl ether as a white solid (0.455 g, 2.27 mmol) in 72%

yield. 1H NMR (400 MHz, CDCl3) δ 7.27-7.34 (m, 2H), 7.10-7.17 (m, 1H), 6.89-7.08 (m,

6H), 3.85 (s, 3H).

Di-3-methoxyphenyl ether (S5, S6)

Prepared according to the general procedure using 3-iodoanisole

(0.717 g, 3.06 mmol), 3-methoxyphenol (0.469 g, 3.77 mmol),

potassium phosphate (1.66 g, 7.82 mmol), copper (I) iodide (60 mg, 0.32 mmol),


was purified by flash column chromatography (eluent: hexanes-ethyl acetate, from 20:1

to 10:1) to give di-3-methoxyphenyl ether as a colorless oil (0.486 g, 2.11 mmol) in 69%

yield. 1H NMR (400 MHz, CDCl3) δ 7.23 (apparent t, J = 8.0 Hz, 2H), 6.64-6.69 (m, 2H),

OOMe OMe

OOMe

OMeO OMe


7

6.58-6.63 (m, 4H), 3.78 (s, 6H). 13C {1H} NMR (100 MHz, CDCl3) δ 160.9 (C), 158.2

(C), 130.0 (CH), 111.1 (CH), 109.0 (CH), 105.0 (CH), 55.3 (CH3O).

Di-4-tert-butylphenyl ether (S4, S7)

Prepared according to the general procedure using 4-iodo-tert-

butylbenzene (1.18 g, 4.54 mmol), 4-tert-butylphenol (0.817 g, 5.43

mmol), potassium phosphate (1.63 g, 7.67 mmol), copper (I) iodide (74 mg, 0.39 mmol),


was purified by flash column chromatography (eluent: hexanes) to give di-4-tert-

butylphenyl ether as a white solid (1.01 g, 3.58 mmol) in 78% yield. 1H NMR (400 MHz,

CDCl3) δ 7.36 (apparent d, J = 9 Hz), 6.97 (apparent d, J = 9 Hz), 1.35 (s, 18H). 13C {1H}

NMR (125 MHz, CDCl3) δ 155.1 (C), 145.8 (C), 126.4 (CH), 118.2 (CH), 34.3 (C), 31.5

(CH3).

Di-3-methylphenyl ether (S8, S9)

Prepared according to the general procedure using 3-iodotoluene

(0.889 g, 4.03 mmol), 3-methylphenol (0.535 g, 4.95 mmol),

potassium phosphate (1.69 g, 7.96 mmol), copper (I) iodide (77 mg, 0.40 mmol),


was purified by flash column chromatography (eluent: hexanes) to give di-3-

methylphenyl ether as an colorless oil (0.655 g, 3.30 mmol) in 82% yield. 1H NMR (400

MHz, CDCl3) δ 7.23 (t, J = 8 Hz, 2H), 6.93 (apparent d, J = 7.5 Hz, 2H), 6.84-6.86

(apparent br s, 2H), 6.81-6.84 (m, J = 8.0, 2 Hz, 2H), 2.35 (s, 6H).13C {1H} NMR (125

MHz, CDCl3) δ 157.3 (C), 139.8 (C), 129.4 (CH), 119.5 (CH), 115.9 (CH), 21.4 (CH3).

4-Methoxyphenyl 4-trifluoromethylphenyl ether (S10)

Prepared according to the general procedure using 4-iodo-

trifluoromethylbenzene (0.853 g, 3.14 mmol), 4-methoxyphenol

(0.474 g, 3.82 mmol), potassium phosphate (1.97 g, 9.28 mmol), copper (I) iodide (58

mg, 0.30 mmol), pyridine-2-carboxylic acid (75 mg, 0.61 mmol) and DMSO (6 ml). The

crude product was purified by flash column chromatography (eluent: hexanes to hexanes-

O

tButBu

OMe Me

O

F3C OMe


8

ethyl acetate, 40:1) to give 4-methoxyphenyl 4-trifluoromethylphenyl ether as a white

solid (0.706 g, 2.63 mmol) in 84% yield. 1H NMR (400 MHz, CDCl3) δ 7.54 (d, J = 9 Hz,

2H), 7.01 (apparent d, J = 9 Hz, 2H), 6.98 (d, J = 8.5 Hz, 2H), 6.93 (apparent d, J = 9 Hz,

2H), 3.83 (s, 3H). 19F {1H} NMR (470 MHz, CDCl3) δ -62.1. 13C {1H} NMR (470 MHz,

CDCl3). 13C {1H} NMR (125 MHz, CDCl3) δ 161.5 (C), 156.7 (C), 148.8 (C), 127.0 (q,

JCF = 3.5 Hz, CH), 124.2 (q, JCF = 272 Hz, CF3), 124.3 (q, JCF = 32 Hz, C), 121.5 (CH),

116.9 (CH), 115.2 (CH), 55.7 (CH3).

4-Methoxyphenyl phenyl ether (S11)

Prepared according to the general procedure using iodobenzene (0.836

g, 4.09 mmol), 4-methoxyphenol (0.654 g, 5.26 mmol), potassium

phosphate (1.73 g, 8.14 mmol), copper (I) iodide (79 mg, 0.42 mmol), pyridine-2-

carboxylic acid (119 mg, 0.967 mmol) and DMSO (8 ml). The crude product was

purified by flash column chromatography (eluent: hexanes to hexanes-ethyl acetate, 20:1)

to give 4-methoxyphenyl phenyl ether as a colorless oil (0.651 g, 3.24 mmol) in 79%

yield. 1H NMR (400 MHz, CDCl3) δ 7.35 (apparent t, J = 8 Hz, 2H), 7.09 (apparent t, J =

7.5 Hz, 1H), 7.04 (apparent d, J = 9.0 Hz, 2H), 7.01 (apparent t, J = 8 Hz, 2H), 6.93

(apparent d, J = 9.0 Hz, 2H), 3.84 (s, 3H).13C {1H} NMR (100 MHz, CDCl3) δ 158.5 (C),

155.8 (C), 150.0 (C), 129.5 (CH), 122.3 (CH), 120.7 (CH), 117.5 (CH), 114.8 (CH), 55.5

(CH3).

Di-2-methylphenyl ether (S11)

Prepared according to the general procedure using 2-iodomethylbenzene

(0.899 g, 4.12 mmol), 2-methylphenol (0.492 g, 4.54 mmol), potassium

phosphate (1.84 g, 8.67 mmol), copper (I) iodide (81 mg, 0.43 mmol),


was purified by flash column chromatography (eluent: hexanes) to give di-2-

methylphenyl ether as a colorless oil (0.692 g, 3.49 mmol) in 85% yield. 1H NMR (400

MHz, CDCl3) δ 7.32 (d, J = 7.5 Hz, 2H), 7.19 (apparent t, J = 8 Hz, 2H), 7.08 (apparent t,

J = 7.5 Hz, 2H), 6.81 (d, J = 8 Hz, 2H), 2.37 (s, 6H). 13C {1H} NMR (100 MHz, CDCl3) δ

155.2 (C), 131.3 (CH), 128.8 (C), 127.0 (CH), 123.0 (CH), 117.6 (CH), 16.1 (CH3).

O

OMe

OMe Me


9

2-(Hexyloxy)naphthalene (S12).

A 25 ml Schlenk flask equipped with a Teflon stopcock and

a magnetic stir bar was charged with anhydrous potassium

carbonate (1.05 g, 7.60 mmol), evacuated and filled with argon. 2-Naphthol (0.721 g,

5.00 mmol), acetone (7.5 ml) and 1-iodohexane (1.64 g, 7.73 mmol) were added. The

flask was sealed and the reaction mixture was stirred at 70 °C for 14 h. The mixture was

cooled to room temperature, evaporated and the residue was partitioned between ether

(150 ml) and water (50 ml). Organic layer was separated, washed with 5% aqueous

potassium hydroxide solution (50 ml), brine (50 ml), and dried over anhydrous sodium

sulfate. The solution was evaporated on silica gel (3.2 g) and the crude product was

purified by flash column chromatography (eluent: hexanes) to give 2-

(hexyloxy)naphthalene as a colorless oil (1.05 g, 4.60 mmol) in 92% yield. 1H NMR (400

MHz, CDCl3) δ 7.77-7.78 (m, 3H), 7.47-7.54 (m, 1H), 7.37-7.43 (m, 1H), 7.17-7.27 (m,

2H), 7.32 (t, J = 6.5 Hz, 2H), 1.86-1.97 (2H), 1.52-1.63 (m, 2H), 1.38-1.51 (m, 4H), 0.97-

1.07 (m, 3H). 13C {1H} NMR (100 MHz, CDCl3) δ 157.1 (C), 134.6 (C), 129.24 (CH),

128.8 (C), 127.6 (CH), 126.6 (CH), 126.2 (CH), 123.4(CH), 119.0 (CH), 106.5 (CH),

67.9 (CH2), 31.6 (CH2), 29.2 (CH2), 25.8 (CH2), 22.6 (CH2), 14.0 (CH3).

4-(Hexyloxy)biphenyl (S13)

Prepared in a similar manner to 2-(hexyloxy)naphthalene using

4-hydroxybiphenyl (0.853 g, 5.01 mmol), 1-iodohexane (1.65 g,

7.78 mmol), potassium carbonate (1.05 g, 7.60 mmol) and

acetone (7.5 ml). The crude product was purified by flash column chromatography

(eluent: hexanes) to give 4-(hexyloxy)biphenyl as white crystals (0.977 mg, 3.84 mmol)

in 76% yield. The product was further purified via recrystallization from methanol. 1H

NMR (400 MHz, CDCl3) δ 7.60 (apparent d, J = 7.5 Hz, 2H), 7.56 (apparent d, J = 8.5

Hz, 2H), 7.46 (apparent t, J = 7.5 Hz, 2H), 7.34 (apparent t, J = 8.5 Hz, 1H), 7.01

(apparent d, J = 7.5 Hz, 2H), 4.03 (t, J = 6.5 Hz, 2H), 1.85 (m, 2H), 1.47-1.59 (m, 2H),

1.34-1.59 (m, 4H), 0.91-1.04 (m, 3H). 13C {1H} NMR (100 MHz, CDCl3) δ 158.7 (C),

O

O


10

140.8 (C), 133.5 (C), 128.7 (CH), 128.0 (CH), 126.7 (CH), 126.5 (CH), 114.7 (CH), 68.0

(CH2), 31.6 (CH2), 29.3 (CH2), 25.7 (CH2), 22.6 (CH2), 14.0 (CH3). General procedure for preparation of benzyl aryl ethers

R1

R2HO

R1 R2

+K2CO3, acetone,

reflux, 3 h

Br O

A 100 ml flask equipped with a reflux condenser, argon inlet and magnetic stir bar, was

charged with anhydrous potassium carbonate (1.66 g, 12 mmol), evacuated and filled

with argon. A phenol (12 mmol), acetone (24 ml), and a benzyl bromide (10 mmol) were

then added and the reaction mixture was refluxed for 3 h. The mixture was cooled down,

and filtered. The filtrate was evaporated and dissolved in methylene chloride (100 ml).

The resulting solution was washed with 5% aqueous solution of potassium hydroxide (50

ml), brine (50 ml) and dried over anhydrous sodium sulfate. The solution was evaporated

and the crude product was either purified by flash column chromatography (liquids) or by

recrystallization (solids).

4-tert-Butylbenzyl phenyl ether.

Prepared according to the general procedure using 4-tert-butylbenzyl

bromide (2.47 g, 10.9 mmol), phenol (1.20 g, 12.8 mmol), potassium

carbonate (2.12 g, 15.3 mmol), and acetone (25 ml). The crude

product was recrystallyzed from hexanes (10 ml) to give 4-tert-butylbenzyl phenyl ether

as white crystals (2.23 g, 9.28 mmol) in 85% yield. 1H NMR (400 MHz, CDCl3) δ 7.47

(apparent d, J = 8.5 Hz, 2H), 7.42 (apparent d, J = 8.5 Hz, 2H), 7.34 (apparent t, J = 8.0

Hz, 2H), 6.98-7.07 (m, 3H), 1.39 (s, 9H). 13C {1H} NMR (100 MHz, CDCl3) δ 158.9 (C),

151.0 (C), 134.0 (C), 129.4 (CH), 127.4 (CH), 125.5 (CH), 120.8 (CH), 114.8 (CH), 69.8

(CH2), 34.6 (C), 31.4 (CH3). Anal. Calcd for C17H20O: C, 84.96; H, 8.39; Found: C, 85.05; H, 8.55.

OtBu


11

3,4-Dimethoxybenzyl 2-methoxyphenyl ether (a model of the α-O-4 lignin ether

linkage) (S14)

Prepared according to the general procedure using 3,4-

dimethoxybenzyl bromide (6.49 g, 28.1 mmol) (15), 2-

methoxyphenol (4.85 g, 39.1 mmol), potassium carbonate (4.82 g,

34.9 mmol), and acetone (60 ml). The crude product was

recrystallized from hexanes (ca 300 ml) to give 3,4-dimethoxybenzyl 2-methoxyphenyl

ether as white crystals (6.05 g, 22.1 mmol) in 78% yield. 1H NMR (500 MHz, CDCl3) δ

6.81-7.03 (m, 7H), 5.08 (s, 2H), 3.88 (s, 6H), 3.87 (s, 3H). 13C {1H} NMR (125 MHz,

CDCl3) δ 149.8 (C), 149.1 (C), 148.7 (C), 129.8 (C), 148.2 (C), 121.5 (CH), 120.7 (CH),

120.0 (CH), 111.9 (CH), 111.0 (CH), 110.8 (CH), 71.2 (CH2), 55.9 (CH3O), 55.8

(CH3O).

1-Methoxy-1-phenylpropane (S16)

A 100 ml two neck flask equipped with reflux condenser and argon inlet and

magnetic stir bar was evacuated, filled with argon and charged with NaH

(60% suspension in mineral oil, 1.40 g, 57.5 mmol) and THF (20 ml). 1-Phenyl-1-

propanol (3.97 g, 29.2 mmol) was added by a syringe and the reaction mixture was stirred

at room temperature for 5 min. Methyl iodide (8.17 g, 57.6 mmol) was added by a

syringe over 2 min and the reaction mixture was refluxed for 2 h, then cooled to room

temperature and carefully quenched with water (40 ml) to give a two-layer mixture. THF

was evaporated, and the crude product was extracted from the resulting aqueous mixture

with dichloromethane (3×25 ml). The combined organic layers were dried over

anhydrous magnesium sulfate and evaporated. The oily residue was distilled in vacuum

(bp. 75-77 °C/18-20 mm) to give 1-methoxy-1-phenylpropane (3.04 g, 20.2 mmol) as a

colorless oil in 69% yield. 1H NMR (400 MHz, CDCl3) δ 7.30-7.37 (m, 2H), 7.27

(apparent d, J = 7.0 Hz, 3H), 4.01 (t, J = 6.5 Hz, 1H), 3.21 (s, 3H), 1.75-1.89 (m, 1H),

1.59-1.73 (m, 1H), 0.87 (t, J = 7.5 Hz, 3H). 13C {1H} NMR (100 MHz, CDCl3) δ 142.2

(C), 128.2 (CH), 127.4 (CH), 126.7 (CH), 85.5 (CH), 56.6 (OCH3), 30.9 (CH2), 10.1

(CH3).

O

MeOOMe

MeO

OMe


12

Methyl 4-tert-butylbenzyl ether (S17)

Under argon, a 100 ml Schlenk flask was charged with sodium

methoxide (0.680 g, 12.6 mmol), methanol (20 ml), magnetic stir bar

and sealed with a septum. To the resulting solution 4-tert-butylbenzyl bromide (2.37 g,

10.4 mmol) was added by a syringe at room temperature for 2 min. The reaction mixture

was stirred for 48 h, then solvent was evaporated and the residue was treated with water

(100 ml). The crude product was extracted with ether (3×50 ml), the combined organic

extracts were washed with brine (50 ml), and dried over anhydrous sodium sulfate. The

product was purified by flash column chromatography (eluent: ethyl acetate-hexanes

1:40) to give methyl 4-tert-butylbenzyl ether as a colorless oil (1.21 g, 6.79 mmol) in

65% yield. 1H NMR (500 MHz, CDCl3) δ 7.43 (apparent d, J = 8.4 Hz, 2H), 7.33

(apparent d, J = 8.4 Hz, 2H), 4.48 (s, 2H), 3.43 (s, 3H), 1.38 (s, 9H). 13C {1H} NMR (125

MHz, CDCl3) δ 150.9 (C), 133.5 (C), 127.9 (CH), 125.5 (CH), 74.8 (CH3), 58.3 (CH2),

34.8 (C), 31.6 (CH3).

Preparation of 1-(3,4-Dimethoxyphenyl)-2-(2-methoxyphenoxy)-l,3-propanediol

(S18- S20) (a model of the β-O-4 lignin ether linkage; modified literature procedure

for an analogous compound) (S21-S23)

A. Methyl 2-(2-methoxyphenoxy)acetate (S24)

A 250 ml two-neck flask equipped with a reflux condenser, argon inlet, and magnetic stir

bar was charged with potassium carbonate (10.40 g, 75.24 mmol), evacuated, and filled

with argon. Acetone (80 ml), methyl bromoacetate (11.59 g, 75.76 mmol), and guaiacol

(6.20 g, 49.9 mmol) were added to the flask via syringe and the reaction mixture was

OOMe OH

OMe

OMe

HO

OH

OMeBr

O

OMe+O

OMe

OMe

O

K2CO3, acetone,reflux, 2.5 h

OMetBu


13

refluxed for 2.5 h, then cooled to room temperature and filtered. The filtrate was

evaporated, to give a pale yellow oil, which was dissolved in methanol and placed in a

fridge (ca -5 °C) overnight. The resulting colorless crystals were filtered, and washed

with cold methanol to give methyl 2-(2-methoxyphenoxy)acetate (8.40 g, 42.8 mmol) in

85% yield. 1H NMR (400 MHz, CDCl3) δ 6.94-7.00 (m, 1H), 6.80-6.92 (m, 3H), 4.68 (s,

2H), 3.86 (s, 3H), 3.77 (s, 3H). 13C {1H} NMR (125 MHz, CDCl3) δ 169.4 (C), 150.0

(C), 147.2 (C), 122.6 (CH), 120.7 (CH), 114.6 (CH), 112.2 (CH), 66.5 (CH2), 55.8 (CH3),

55.0 (CH3).

B. Methyl 3-(3,4-dimethoxyphenyl)-3-hydroxy-2-(2-methoxyphenoxy)propanoate

O

OMe

OMe

O

THF 0 oC,LDA

30 min

O CO2MeLi+

MeOOMe

CHO

OMeO

OMe OH

MeO O OMe

OMe

THF, -78 oC,2 h

A 250 ml Schlenk flask equipped with a magnetic stir bar and septum cap, was evacuated

and filled with argon. THF (30 ml) and diisopropylamine (3.1 ml, 22 mmol) were added

by a syringe. The resulting solution was cooled to 0 °C and a 1.6 M solution of n-

butyllithium in hexanes (13.75 ml, 22.00 mmol) was added by a syringe for 3 min. The

reaction mixture was stirred for 30 min, then cooled to -78 °C and a solution of methyl 2-

(2-methoxyphenoxy)acetate (3.92 g, 20.0 mmol) in THF (40 ml) was added dropwise for

15 min to give a pale yellow solution. The solution was stirred for 15 min and a solution

of 3,4-dimethoxybenzaldehyde (3.32 g, 20.0 mmol) in THF (20 ml) was added dropwise

for 5 min. The reaction mixture was stirred for 2 h, then quenched at -78 °C with a

saturated solution of ammonium chloride (75 ml), and warmed up to room temperature to

give a two-layer mixture. The organic layer was separated, and the aqueous layer was

extracted with ethyl acetate (3×50 ml). The combined organic layers were washed with

brine (50 ml), and dried over anhydrous sodium sulfate. The crude product was purified

by flash column chromatography (eluent: ethyl acetate-hexanes from 1:2 to 1:1) to give

methyl 3-(3,4-dimethoxyphenyl)-3-hydroxy-2-(2-methoxyphenoxy)propanoate (3.59 g,

9.91 mmol) as a white solid in 49% yield. 1H NMR (500 MHz, CDCl3), major isomer δ

6.78-7.06 (m, 7H), 5.13 (t, J = 5.5 Hz, 1H), 4.73 (d, J = 5.0 Hz, 1H), 3.87 (s, 3H), 3.86 (s,


14

3H), 3.84 (s, 3H), 3.71 (d, J = 6.0 Hz, 1H), 3.68 (s, 3H); minor isomer δ 6.78-7.06 (m,

7H), 5.07 (dd, J = 7.0, 3.5 Hz, 1H), 4.50 (d, J = 7.0 Hz, 1H), 3.87 (s, 3H), 3.86 (s, 3H),

3.85 (s, 3H), 3.60 (s, 3H). 13C {1H} NMR (125 MHz, CDCl3) major + minor δ 169.9,

169.8, 150.5, 150.3, 149.0, 148.9, 148.8, 148.7, 147.2, 147.1, 131.7, 130.6, 123.9, 121.1,

121.0, 119.4, 119.2, 118.8, 118.1, 112.3, 110.7, 110.0, 109.8, 85.3, 83.9, 74.7, 73.8, 55.8,

55.7, 52.1, 52.0. Ratio of diastereomers (major to minor): 4.5. Anal. Calcd for C19H22O7: C, 62.97; H, 6.12; Found: C, 62.68; H, 6.07.

C. 1-(3,4-Dimethoxyphenyl)-2-(2-methoxyphenoxy)-l,3-propanediol (S18)

OOMe OH

OMe

OMe

HO

OOMe OH

MeO O OMe

OMe NaBH4THF/water (3:1),

rt, 22 h A 250 ml Schlenk flask was charged with methyl 3-(3,4-dimethoxyphenyl)-3-hydroxy-2-

(2-methoxyphenoxy)propanoate (3.15 g, 8.69 mmol), a magnetic stir bar and sealed with

a septum. The flask was evacuated, filled with argon and a 3:1 mixture of THF/water (80

ml) was added. Sodium borohydride (43.6 mmol) was added to the solution in two

portions (2×0.825 g) over about 1 h, and the stirring was continued for 22 h. The

resulting mixture was evaporated to ca. 20 ml, diluted with 80 ml of water and the crude

product was extracted with ethyl acetate (3×60 ml). The combined extracts were washed

with brine (50 ml) and dried over anhydrous sodium sulfate. The product was purified by

flash column chromatography (eluent: ethyl acetate-hexanes from 1:1 to 3:1) to give 1-

(3,4-dimethoxyphenyl)-2-(2-methoxyphenoxy)-l,3-propanediol (2.32 g, 6.94 mmol) as a

white solid in 80% yield. 1H NMR (500 MHz, CDCl3), major + minor diastereoisomers δ

6.80-7.14 (m, 7H), 4.95-5.01 (m, 1H), 4.13-4.19 (m, 0.77 H, major diastereoisomer), 3.99

(m, 0.35 H, minor isomer), 3.82-3.95 (m, 10H), 3.44-3.74 (m, 2H), 2.69-2.82 (1H), 1.71-

1.83 (m, 0.3H). 13C {1H} NMR (125 MHz, CDCl3) major + minor diastereomers δ 151.6,

151.3, 149.1, 149.0, 148.9, 148.5, 147.6, 146.9, 132.5, 132.1, 124.2 (2C), 121.6 (2C),

121.0, 120.9, 119.6, 118.4, 112.2, 111.0, 109.9, 109.2, 89.4, 87.4, 73.9, 72.7, 61.0, 60.7,

55.9 (C). Ratio of diastereomers (major to minor): 2.2. MS (ESI+) m/z: 357.3 [M+Na]+.


15

4. Stability of the Ni(COD)2/PCy3 under the Conditions of Reductive Cleavage of

Aromatic C-O bonds

Figure S1. Attempted hydrogenolysis of diphenyl ether catalyzed by Ni(COD)2/PCy3.

+ H2 m-xylene,120 oC, 16 h

O

HO+X

+

(0.2 equiv.)

+

+

conversion: ca 1%

(1 bar)Ni(COD)2

44% 7%products of the C-P bond

cleavage in PCy3

(0.4 equiv.)(1 equiv.)

The yields were based on theamount of PCy3, assuming thatonly one cyclohexyl group of thephosphine ligand is converted to the hydrocarbons.

(traces, ~1%)P 3

Procedure:

The reaction was conducted according to General Procedure A (p. 29) with Ni(COD)2

(8.4 mg, 3.1⋅10-2 mmol), PCy3 (16.7 mg, 5.95⋅10-2 mmol), diphenyl ether (25.4 mg, 0.155

mmol), dodecane (internal standard for GC, 25.8 mg) and m-xylene (0.8 ml) at 120 °C for

16 h. After saturation of the reaction mixture with hydrogen at room temperature, the

yellow color changed to dark red within 15 min; the final color of the reaction mixture

after heating for 16 h was dark brown. GC and GC/MS analyses of the reaction mixture

showed low conversion of diphenyl ether (~1%). Benzene was detected in only trace

amounts (1%). Cyclohexane (m/z 84) and cyclohexene (m/z 82) from cleavage of the C-P

bond in PCy3 were observed in 44% and 7% yields, respectively. The yields were based

on the amount of PCy3, assuming that only one cyclohexyl group of the phosphine ligand

is converted to the hydrocarbons. Cyclooctane (m/z 112) from hydrogenation of COD

was also detected.

Decomposition of PCy3 under the Conditions of Hydrogenolysis

H2 m-xylene,120 oC, 16 h

+

(1 equiv.)

+ +(1 bar)

Ni(COD)2

55% 7%(2 equiv.)

P 3

The reaction was conducted according to General Procedure A (p. 29) with Ni(COD)2

(8.4 mg, 3.1⋅10-2 mmol), PCy3 (18.0 mg, 6.42⋅10-2 mmol), dodecane (internal standard for

GC, 24.4 mg) and m-xylene (0.8 ml) at 120 °C for 16 h. The color changes were similar


16

to those observed for the above procedure of the reaction with diphenyl ether. GC and

GC/MS analyses of the reaction mixture showed the formation of cyclohexane (m/z 84)

and cyclohexene (m/z 82) in 55% and 7% yields, respectively. The yields were based on

the amount of PCy3, assuming that only one cyclohexyl group of the phosphine ligand is

converted to the hydrocarbons. Cyclooctane (m/z 112) from hydrogenation of COD was

also detected.

Figure S2. Attempted Reductive Cleavage of Anisole with Triethylsilane Catalyzed

by the Combination of Ni(COD)2/PCy3.

+ Et3SiH toluene,140 oC, 16 h

OMeX

+

(0.2 equiv.)

+

+

conversion ca 1%(25 equiv.)

Ni(COD)2

18% 41%products of the C-P bond

cleavage in PCy3

(0.4 equiv.)(1 equiv.)

The yields were based on theamount of PCy3, assuming thatonly one cyclohexyl group of thephosphine ligand is converted to the hydrocarbons.

(traces, ~1%)P 3

The reaction was conducted according to the General Procedure (p. 18) with Ni(COD)2

(8.3 mg, 3.0⋅10-2 mmol), PCy3 (16.7 mg, 5.95⋅10-2 mmol), anisole (16.0 mg, 0.148

mmol), triethylsilane (600 µl, 3.76 mmol), dodecane (internal standard for GC, 23.2 mg)

and toluene (0.3 ml) at 140 °C for 16 h. The starting reaction mixture was yellow; after

heating at 140 °C for 5 min, the color changed to dark red; the color after heating at 140

°C for 16 h was dark brown, and nickel black was observed. GC and GC/MS analyses of

the reaction mixture showed low conversion of anisole (ca 1%). Cyclohexane (m/z 84)

and cyclohexene (m/z 82) from cleavage of the C-P bond in PCy3 were observed in 18%

and 41% yields, respectively. These yields were based on the amount of PCy3, assuming

that only one cyclohexyl group of the phosphine ligand is converted to the hydrocarbons.


17

Decomposition of PCy3 under the Conditions of Reductive Cleavage with

Triethylsilane

Et3SiH toluene,140 oC, 16 h

+

(1 equiv.)

+ +

(125 equiv.)

Ni(COD)2

8% 36%(2 equiv.)

P 3

The reaction was conducted according to General Procedure (p. 18) with Ni(COD)2 (8.5

mg, 3.1⋅10-2 mmol), PCy3 (16.7 mg, 6.42⋅10-2 mmol), dodecane (internal standard for GC,

19.2 mg) and toluene (0.3 ml) at 140 °C for 16 h. The color changes were similar to those

for the above procedure containing anisole. GC and GC/MS analyses of the reaction

mixture showed the formation of cyclohexane (m/z 84) and cyclohexene (m/z 82) in 8%

and 36% yields, respectively. The yields were based on the amount of PCy3, assuming

that only one cyclohexyl group of the phosphine ligand is converted to the hydrocarbons.

Cyclooctane (m/z 112) from hydrogenation of COD was also detected.


18

5. Nickel-NHC Catalyzed Reductive Cleavage of Aryl and Benzyl Ethers with

Hydride Donors

Reactions were conducted in 4 ml screw thread vials (15 mm×45 mm; supplied by

Kimble Chase) equipped with Teflon-lined screw caps (13 mm diameter, 425 GPI thread;

supplied by Qorpak) and Teflon-coated magnetic stir bars (3 mm×10 mm; supplied by

Fisher Scientific). The vials were heated in an aluminum heating block; the reaction

temperature was measured by a thermocouple immersed into a silicone oil in a separate 4

ml vial, placed in the same heating block.

General procedure

In a glovebox, a 4 ml vial was charged with Ni(COD)2 (0.75⋅10-2-3.0⋅10-2 mmol, 5-20

mol%), a carbene ligand salt (1.5⋅10-2-6.0⋅10-2 mmol, 10-40 mol%), NaOtBu (0.375

mmol) and a magnetic stir bar. After 0.3 ml of 0.5 M solution of aryl or benzyl ether

(0.15 mmol) in toluene and dodecane (internal standard for GC) were added, the mixture

was stirred for 3 min and DIBAL (0.375 mmol, 1M solution in hexanes) or triethylsilane

(0.375-1.50 mmol) was added by a syringe. Note, for reductions with Li(Al(OtBu)3H, the

reductant was added in the beginning together with other solid reagents and the reaction

mixture was diluted with additional 0.5 ml of toluene. The resulting dark brown mixture

was stirred for 1 min. The reaction vial was sealed with a screw cap, removed from the

glovebox and heated at 60-140 °C for 16-96 h (see Table S2). After cooling to room

temperature, dark brown to black reaction mixture was diluted with ether (1 ml) and

carefully quenched at 0 °C with 1 ml of 1.5 M aqueous HCl. The resulting mixture was

stirred for 10 min for reactions with triethylsilane or 40 min when DIBAL or

Li(Al(OtBu)3H were used. The organic layer was separated, the aqueous layer was

extracted with ether (1 ml), and the combined organic layers were passed through a short

pad of Celite and subjected to GC and GC/MS analyses. The products were all known

compounds and were identified using GC/MS and GC by comparison of the mass spectra

and retention times of the products with those of authentic compounds.


19

Discussion

We initially tested nickel-NHC catalysts for the reduction of the C-O bond of

diphenyl ether in the presence of the hydride donors, DIBALH (diisobutylaluminum

hydride), LiAl(OtBu)3H, and Et3SiH in place of H2, because of the convenience of

evaluating catalysts for reactions with liquid and solid reagents. These reactions were

conducted with the combination of a nickel(0) precursor, Ni(COD)2 or Ni(acac)2 (acac,

acetylacetonate), and an NHC ligand formed in situ by deprotonation of the

corresponding salt NHC⋅HX with a base (NaOtBu) (Table S1). We found that the highest

yields of the products from aromatic C-O bond cleavage were obtained with Ni(COD)2 as

the source of nickel, with SIPr⋅HCl (shown in Fig. S3) as ligand precursor, and the

aluminium hydride donors DIBALH and LiAl(OtBu)3H (2.5 equiv.) in the presence of

NaOtBu (2.5 equiv.) as a base in toluene (Table S1 and S2). Although the base was added

initially to generate the free carbene from the salt form, the highest yields of the products

were obtained with an excess of base (Table S1). Under these conditions, cleavage of

diphenyl ether with DIBALH proceeded, even at 60 °C, to give benzene and phenol in

nearly quantitative yields in the presence of 20 mol% Ni(COD)2 and 40 mol% of

SIPr⋅HCl (Table S2, Entry 1). Reaction with LiAl(OtBu)3H occurred with 10 mol% of the

catalyst at 100 °C to give the arene and phenol in 82% and 86% yields (Table S2, Entry

2). Cleavage with the milder reagent Et3SiH (10 equiv.) occurred with less catalyst (5%)

but gave moderate yields of the products (Table S2, Entry 3).

This class of catalyst, in tandem with either aluminum hydrides or silane reducing

agents, was then tested for the reductive cleavage of a series of unactivated aryl and

benzyl ethers. In addition to the cleavage of diphenyl ether, reduction of a cyclic diaryl

ether, dibenzofuran, gave 2-hydroxybiphenyl in nearly quantitative yield (99%) with

triethylsilane as hydride source at 120 °C for 48 h (Table S2, Entry 4). 4-

Methoxybiphenyl was cleaved with triethylsilane, DIBALH and LiAl(OtBu)3H to form

excellent yields of biphenyl (89%-99%) in the presence of the Ni-SIPr catalyst (Table S2,

Entries 5-7). The same system catalyzed reduction of the fully unactivated alkyl ether

anisole with DIBALH and LiAl(OtBu)3H to give benzene in 87% and 62% yields,


20

respectively, at 120 °C (Table S2, Entries 8-9). Cleavage of the aromatic C-O bond in

anisole with the milder reductant triethylsilane was induced by Ni(COD)2 in combination

with the bulkier carbene ligand IPrMe (shown in Fig. S3) to give benzene in 77% yield at

140 °C for 96 h (Table S2, Entry 10). Under the same conditions the reaction catalyzed

by Ni(COD)2 and PCy3 failed to form products from cleavage of anisole, instead forming

cyclohexane and cyclohexene from the phosphine ligand (Fig. S2).

The Ni-SIPr system also catalyzed the reduction of unactivated benzyl ethers (Table S2,

Entries 11-14). In this case, cleavage occurred at the benzylic C-O bond. Reduction of

this C-O bond in an alkyl benzyl ether proceeded much more slowly than reduction of

aryl benzyl ethers and required similar conditions to those for the cleavage of alkyl aryl

ethers. Thus, reduction of α-ethylbenzyl methyl ether with aluminum hydrides occurred

at 120 °C for 16 h (Table S2, Entries 11, 12), whereas reduction of phenyl tert-

butylbenzyl ether was complete at 80 °C in 16 h (Table S2, Entries 13, 14).


21

Table S1. Selected Results on the Effect of Ligand, Nickel and Hydride Source and Base

Amount on the Reductive Cleavage of Diphenyl Ether. See General Procedure (p. 18). O

+ 10-40% SIPr·HCl"H-" NaOtBu, toluene,

temp, 16 h+HO5-10% Ni(COD)2,

Entry Ligand “Ni” Ni, mol% “H-” “H-”, equiv.

Base, equiv. T, °C Conversion, % Yield of

benzene, % Yield of

phenol, % 1 SImBu⋅HBF4 Ni(COD)2 10 Et3SiH 2.5 2.5 100 20 20 16 2 SIMes⋅HBF4 Ni(COD)2 10 Et3SiH 2.5 2.5 100 46 44 44 3 IMes⋅HCl Ni(COD)2 10 Et3SiH 2.5 2.5 100 52 48 52 4 IPr⋅HCl Ni(COD)2 10 Et3SiH 2.5 2.5 100 58 38 54 5 SIPr⋅HCl Ni(COD)2 10 Et3SiH 2.5 2.5 100 65 42 65 6 SIPr⋅HCl Ni(COD)2 10 Et3SiH 2.5 0.5 100 29 9 21

7 SIPr⋅HCl Ni(COD)2 5 Et3SiH 10 2.5 100 70 56 70 8 IPr⋅HCl Ni(COD)2 5 Et3SiH 10 2.5 100 50 47 50 9 IPr⋅HCl Ni(COD)2 10 DIBALH 2.5 2.5 100 2 0 0 10 SIPr⋅HCl Ni(COD)2 10 DIBALH 2.5 2.5 100 41 41 37 11 IPr⋅HCl Ni(COD)2 10 LiAl(OtBu)3H 2.5 2.5 100 83 75 75 12 SIPr⋅HCl Ni(COD)2 10 LiAl(OtBu)3H 2.5 2.5 100 90 82 86 13 SIPr⋅HCl Ni(COD)2 20 DIBALH 2.5 2.5 60 100 99 99 14 SIPr⋅HCl Ni(COD)2 20 DIBALH 2.5 0.44 60 0 0 0 15 SIPr⋅HCl Ni(acac)2 20 DIBALH 2.5 2.5 60 35 37 10 16 IPr⋅HCl Ni(COD)2 20 DIBALH 2.5 2.5 60 87 87 60 17 - Ni(COD)2 20 DIBALH 2.5 2.5 60 11 11 7 18 IPr⋅HCl Ni(COD)2 20 LiAl(OtBu)3H 2.5 2.5 60 1 0 0 19 SIPr⋅HCl Ni(COD)2 20 LiAl(OtBu)3H 2.5 2.5 60 0 0 0

Figure S3. Carbene Ligands Used in the Study

N N

Cl

IMes HCl

N N

SIMes HBF4

BF4

N N

BF4

SImBu HBF4

N N

IPr HCl

N N

SIPr HCl

Cl Cl


22

Table S2. Reductive Cleavage of Aryl and Benzyl Ethers with Hydride Donors. See

General Procedure (p. 18).

R1 OR2 + "H-" 10-40% SIPr·HClNaOtBu (2.5 equiv),

5-20% Ni(COD)2,

R1 = Aryl, Benzyl; R2 = Aryl, Methyl

R1 H

"H-" = DIBALH, LiAl(OtBu)3H, Et3SiH

+

Entry Aryl/Benzyl ether Ni, mol%Hydride donor T, °C Time, h R1H, % R2OH, %

23

LiAl(OtBu)3HEt3SiH*

105

100100

1616

8256†

8670

O

4 Et3SiH 20 120 48 99

OMe

OMe

7 Et3SiH§ 20 120 56 89 nd6 LiAl(OtBu)3H 20 120 32 90 nd

Ph

OMe

Et

12 LiAl(OtBu)3H 20 120 56 91 nd

14 LiAl(OtBu)3H 20 80 16 82 99OPh

tBu

*10 equiv. of Et3SiH. †Phenyltriethylsilane as a side product. ‡Not determined. §25 equiv. of Et3SiH. IIIPrMe·HCl as a ligand. ¶Benzene (15%) as a side product. #4-tert-butylbenzyl alcohol (16%) as a side product.

R2OH(2.5 equiv) toluene

10 Et3SiH§,II 20 140 96 77 nd9 LiAl(OtBu)3H 20 120 36 62 nd

1 DIBAL 20 100 16 99 99O

8 DIBALH 20 120 40 87 nd

5 DIBALH 20 120 16 99 nd‡

11 DIBALH 20 120 16 94 nd

13 DIBALH 20 80 16 79¶ 55#

Conv, %

9070

100

9191

92

100

8485

100

94

100

100

100


23

Reductive cleavage of diphenyl ether with DIBALH (Table S2, Entry 1) O

+ 40% SIPr·HClDIBALH NaOtBu, toluene,

60 °C, 16 h+

HO20% Ni(COD)2,

99% 99%

The reaction was conducted according to the general procedure with Ni(COD)2 (8.2 mg,

3.0⋅10-2 mmol), SIPr⋅HCl (25.4 mg, 5.95⋅10-2 mmol), tBuONa (40.2 mg, 0.418 mmol),

diphenyl ether (25.8 mg, 0.152 mmol), DIBALH (0.375 ml of 1M solution in hexanes,

0.375 mmol), dodecane (internal standard for GC, 6.3 mg) and toluene (0.3 ml) at 60 °C

for 16 h. GC and GC/MS analyses of the reaction mixture showed complete conversion

of diphenyl ether and formation of benzene (78 m/z) and phenol (94 m/z) in 99% yields.

Reductive cleavage of diphenyl ether with LiAl(OtBu)3H (Table S2, Entry 2) O

+ 20% SIPr·HClLiAl(OtBu)3H NaOtBu, toluene,

100 °C, 16 h+

HO10% Ni(COD)2,

82% 86%


1.5⋅10-2 mmol), SIPr⋅HCl (14.0 mg, 3.28⋅10-2 mmol), NaOtBu (38.4 mg, 0.400 mmol),

diphenyl ether (26.4 mg, 0.155 mmol), LiAl(OtBu)3H (96.4 mg, 0.379 mmol), dodecane

(internal standard for GC, 6.4 mg) and toluene (0.8 ml) at 100 °C for 16 h. GC and

GC/MS analyses of the reaction mixture showed formation of benzene (78 m/z) and

phenol (94 m/z) in 82% and 86% yields respectively at 90% conversion of diphenyl

ether.

Reductive cleavage of diphenyl ether with Et3SiH (Table S2, Entry 3) O

+ 10% SIPr·HClEt3SiH NaOtBu, toluene,100 °C, 16 h

+HO5% Ni(COD)2,

56% 70%

+SiEt3



diphenyl ether (25.8 mg, 0.152 mmol), Et3SiH (240 µl, 174 mg, 1.50 mmol), dodecane


GC/MS analyses of the reaction mixture showed formation of benzene (m/z 78) and


24

phenol (m/z 94) in 56% and 70% yields respectively at 70% conversion of diphenyl

ether. Triethylphenylsilane (m/z 163, [M-Et]+) was detected as a main side product.

Et3SiOtBu (m/z 173 [M-Et]+) was the major silicon product.

Reductive cleavage of dibenzofuran with Et3SiH (Table S2, Entry 4)

+ 40% SIPr·HClEt3SiH NaOtBu, toluene,

120 °C, 48 h

20% Ni(COD)2,

O

HO

99% The reaction was conducted according to the general procedure with Ni(COD)2 (8.3 mg,


dibenzofuran (25.2 mg, 0.150 mmol), Et3SiH (60 µl, 43.7 mg, 0.376 mmol), dodecane


GC/MS analyses of the reaction mixture showed formation of 2-hydroxybiphenyl (m/z

170) in 99% yield. Et3SiOtBu (m/z 173 [M-Et]+) was the major silicon product.

Reductive cleavage of 4-methoxybiphenyl with DIBALH (Table S2, Entry 5)

OMe+

40% SIPr·HClDIBALH NaOtBu, toluene,

120 °C, 16 h

20% Ni(COD)2,

99%Ph Ph


3.2⋅10-2 mmol), SIPr⋅HCl (29.9 mg, 7.00⋅10-2 mmol), tBuONa (43.4 mg, 0.452 mmol), 4-

methoxybiphenyl (28.1 mg, 0.151 mmol), DIBALH (0.375 ml of 1M solution in

hexanes, 0.375 mmol), dodecane (internal standard for GC, 14 mg) and toluene (0.3 ml)

at 120 °C for 16 h. GC and GC/MS analyses of the reaction mixture showed complete

consumption of 4-methoxybiphenyl and formation of biphenyl (m/z 154) in 99% yield.

Reductive cleavage of 4-methoxybiphenyl with LiAl(OtBu)3H (Table S2, Entry 6)

OMe+

40% SIPr·HClLiAl(OtBu)3H NaOtBu, toluene,120 °C, 32 h

20% Ni(COD)2,

90%Ph Ph


3.1⋅10-2 mmol), SIPr⋅HCl (25.8 mg, 6.04⋅10-2 mmol), NaOtBu (36.6 mg, 0.381 mmol), 4-

methoxybiphenyl (25.5 mg, 0.149 mmol), LiAl(OtBu)3H (95.3 mg, 0.371 mmol),


25

dodecane (internal standard for GC, 20 mg) and toluene (0.8 ml) at 120 °C for 32 h. GC

and GC/MS analyses of the reaction mixture showed formation of biphenyl (m/z 154) in

90% yield at 91% conversion of 4-methoxybiphenyl.

Reductive cleavage of 4-methoxybiphenyl with Et3SiH (Table S2, Entry 7)

OMe+

40% SIPr·HClEt3SiH NaOtBu, toluene,

140 °C, 56 h

20% Ni(COD)2,

89%Ph Ph



methoxybiphenyl (27.6 mg, 0.150 mmol), Et3SiH (600 µl, 437 mg, 3.76 mmol), dodecane


GC/MS analyses of the reaction mixture showed the formation of benzene (m/z 78) in

89% yield at 91% conversion of 4-methoxybiphenyl. Et3SiOtBu (m/z 173 [M-Et]+) was

the major silicon product.

Reductive cleavage of anisole with DIBALH (Table S2, Entry 8)

OMe+

40% SIPr·HBF4DIBALH NaOtBu, toluene,

120 °C, 40 h

20% Ni(COD)2,


3.1⋅10-2 mmol), SIPr⋅HBF4 (30.1 mg, 6.29⋅10-2 mmol), tBuONa (43.4 mg, 0.452 mmol),

anisole (16.4 mg, 0.15 mmol), DIBALH (0.375 ml of 1M solution in hexanes, 0.375

mmol), dodecane (internal standard for GC, 10.9 mg) and toluene (0.3 ml) at 120 °C for

40 h. GC and GC/MS analyses of the reaction mixture showed the formation of benzene

(m/z 78) in 87% yield at 94% conversion of anisole.


26

Reductive cleavage of anisole with LiAl(OtBu)3H (Table S2, Entry 9)

OMe+

40% SIPr·HClLiAl(OtBu)3H NaOtBu, toluene,120 °C, 32 h

20% Ni(COD)2,



anisole (16.4 mg, 0.151 mmol), LiAl(OtBu)3H (91.8 mg, 0.375 mmol), dodecane (internal

standard for GC, 11.9 mg) and toluene (0.8 ml) at 120 °C for 40 h. GC and GC/MS

analyses of the reaction mixture showed the formation of benzene (m/z 78) in 62% yield

at 85% conversion of anisole.

Reductive cleavage of anisole with Et3SiH (Table S2, Entry 10)

OMe+

40% IPrMe·HClEt3SiH NaOtBu, toluene,

140 °C, 96 h

20% Ni(COD)2,



anisole (17.8 mg, 0.165 mmol), Et3SiH (600 µl, 437 mg, 3.76 mmol), dodecane (internal

standard for GC, 12.8 mg) and toluene (0.3 ml) at 140 °C for 96 h. GC and GC/MS

analyses of the reaction mixture showed the formation of benzene (m/z 78) in 77% yield

at 84% conversion of anisole. Et3SiOtBu (m/z 173 [M-Et]+) was the major silicon

product.

Reductive cleavage of 1-methoxy-1-phenylpropane with DIBALH (Table S2,

Entry 11)


120 °C, 16 h

20% Ni(COD)2,

94%

OMe



methoxy-1-phenylpropane (23.3 mg, 0.155 mmol), DIBALH (0.240 ml of 1M solution


27

in hexanes, 0.240 mmol), dodecane (internal standard for GC, 11.5 mg) and toluene (0.3

ml) at 120 °C for 16 h. GC and GC/MS analyses of the reaction mixture showed

complete consumption of 1-methoxy-1-phenylpropane and formation of 1-phenylpropane

(m/z 120) in 94% yield.

Reductive cleavage of 1-methoxy-1-phenylpropane with LiAl(OtBu)3H (Table S2,

Entry 12)


120 °C, 56 h

20% Ni(COD)2,

91%

OMe



methoxy-1-phenylpropane (22.0 mg, 0.146 mmol), LiAl(OtBu)3H (95.7 mg, 0.376

mmol), dodecane (internal standard for GC, 8.8 mg) and toluene (0.8 ml) at 120 °C for 56

h. GC and GC/MS analyses of the reaction mixture showed the formation of 1-

phenylpropane (m/z 120) in 91% yield at 92% conversion of 1-methoxy-1-

phenylpropane.

Reductive cleavage of 4-tert-butylbenzyl phenyl ether with DIBALH (Table S2,

Entry 13)


80 °C, 16 h

O +10% Ni(COD)2,

79% 15%tBu tBu

Me+ +tBu

OHHO

55%16% The reaction was conducted according to the general procedure with Ni(COD)2 (8.3 mg,


tert-butylbenzyl phenyl ether (36.1 mg, 0.150 mmol), DIBALH (0.210 ml of 1M

solution in hexanes, 0.210 mmol), dodecane (internal standard for GC, 12.6 mg) and

toluene (0.3 ml) at 80 °C for 16 h. GC and GC/MS analyses of the reaction mixture

showed complete consumption of 4-tert-butylbenzyl phenyl ether and formation of 4-

tert-butyltoluene (m/z 148), benzene (m/z 78), phenol (m/z 94), and 4-tert-butylbenzyl

alcohol (m/z 164) in 79%, 15%, 16% and 55% yields respectively.


28

Reductive cleavage of 4-tert-butylbenzyl phenyl ether with LiAl(OtBu)3H (Table S2,

Entry 14)


80 °C, 32 h

O +10% Ni(COD)2,

82% 99%tBu tBu

Me HO



tert-butylbenzyl phenyl ether (36.1 mg, 0.150 mmol), LiAl(OtBu)3H (92.2 mg, 0.363

mmol), dodecane (internal standard for GC, 36.9 mg) and toluene (0.3 ml) at 80 °C for 32

h. GC and GC/MS analyses of the reaction mixture showed complete consumption of 4-

tert-butylbenzyl phenyl ether and formation of 4-tert-butyltoluene (m/z 148), and phenol

(m/z 94) in 82% and 99% yields respectively.


29

6. Nickel-NHC Catalyzed Selective Hydrogenolysis of Aryl and Benzyl Ethers

Reactions were conducted in 15 ml Schlenk tubes (exact volume 14.8 ml, outer diameter

of the tube 16 mm) equipped with Teflon-stopcocks and Teflon-coated magnetic stir bars

(3 mm × 10 mm; supplied by Fisher Scientific). The reported pressure of hydrogen refers

to the readings from the gauge of the gas cylinder at room temperature. The reaction

tubes were heated in an oil bath; the reaction temperature refers to the temperature of the

oil bath.

General Procedure A

In a glovebox, a 15 ml Schlenk tube equipped with a Teflon-stopcock was charged with

Ni(COD)2 (0.75⋅10-2-3.0⋅10-2 mmol, 5-20 mol%), SIPr⋅HCl (1.5⋅10-2- 6.0⋅10-2 mmol, 10-

40 mol%), NaOtBu (0.375 mmol) and a magnetic stir bar. Then a solution of aryl or

benzyl ether (0.15 mmol) and dodecane internal standard for GC) in m-xylene (0.8 ml)

were added, and the mixture was stirred for 3 min. The Schlenk tube was sealed with the

Teflon stopcock and removed form the glovebox. The reaction mixture was degassed via

two cycles of freeze-pump-thaw and the tube was pressurized with 1 bar (15 psi) of

hydrogen at room temperature; saturation with hydrogen leads to slightly noticeable

change in color from dark brown to dark red brown. The tube was sealed with the Teflon

stopcock and heated in an oil bath at 80, 100 or 120 °C for 16-48 h. The resulting dark

brown to black mixture was cooled to room temperature, diluted with ether (1 ml) and

quenched with 1.5 M aqueous HCl (1 ml) followed by stirring for 15 min. The organic

layer was separated and the aqueous layer was extracted with 1 ml of ether. The

combined organic layers were passed through a short pad of Celite and subjected to GC

and GC/MS analyses. The products were all known compounds and were identified using

GC/MS and GC by comparison of the mass spectra and retention times of the products

with those of commercially available authentic compounds.

General Procedure B (Hydrogenolysis in the Presence of 1 equiv. of AlMe3)

The procedure is similar to General Procedure A, but includes addition of AlMe3 (2 M in

toluene, 75 µl, 0.15 mmol) after mixing of all reagents and stirring for 3 min.


30

Hydrogenolysis of diphenyl ether (Table 1, Entry 1)

O+

40% SIPr·HClH2 NaOtBu, m-xylene,

120 °C, 16 h+

HO20% Ni(COD)2,

99% 99%(1 bar at rt)

The reaction was conducted according to General Procedure A with Ni(COD)2 (8.3 mg,


diphenyl ether (26.4 mg, 0.155 mmol), dodecane (internal standard for GC, 8.8 mg) and

m-xylene (0.8 ml) at 120 °C for 16 h. GC and GC/MS analyses of the reaction mixture

showed the formation of benzene (78 m/z) and phenol (94 m/z) in 99% and 99% yields

respectively at full conversion of diphenyl ether. Hydrogenolysis with SIPr⋅HBF4 as a

ligand precursor led to the identical product yields.

Hydrogenolysis of diphenyl ether (Table 1, Entry 2) O

+ 20% SIPr·HClH2 NaOtBu, m-xylene,

120 °C, 32 h+

HO10% Ni(COD)2,

82% 87%(1 bar at rt)



diphenyl ether (26.0 mg, 0.152 mmol), dodecane (internal standard for GC, 10 mg) and

m-xylene (0.8 ml) at 120 °C for 32 h. GC analysis of the reaction mixture showed the

formation of benzene and phenol in 82% and 87% yields respectively at 87% conversion

of diphenyl ether.

Hydrogenolysis of diphenyl ether (Table 1, Entry 3) O

+ 10% SIPr·HClH2 NaOtBu, m-xylene,120 °C, 32 h

+HO5% Ni(COD)2,

59% 54%(1 bar at rt)



diphenyl ether (25.3 mg, 0.149 mmol), dodecane (internal standard for GC, 14.5 mg) and

m-xylene (0.8 ml) at 120 °C for 32 h. GC analysis of the reaction mixture showed the


31

formation of benzene and phenol in 59% and 54% yields respectively at 59% conversion

of diphenyl ether.

Hydrogenolysis of di-3-methylphenyl ether (Table 1, Entry 4) O


120 °C, 16 h+

HO20% Ni(COD)2,

96% 99%(1 bar at rt) Me

Me Me Me


3.1⋅10-2 mmol), SIPr⋅HCl (29.3 mg, 6.86⋅10-2 mmol), NaOtBu (39.1 mg, 0.407 mmol), di-

3-methylphenyl ether (30.6 mg, 0.154 mmol), dodecane (internal standard for GC, 35.6

mg) and m-xylene (0.8 ml) at 120 °C for 16 h. GC and GC/MS analyses of the reaction

mixture showed the formation of toluene (92 m/z) and 3-methylphenol (108 m/z) in 96%

and 99% yields respectively at full conversion of di-3-methylphenyl ether.

Hydrogenolysis of di-3-methoxyphenyl ether (Table 1, Entry 5) O


120 °C, 16 h+HO20% Ni(COD)2,

65% 83%(1 bar at rt) MeO

MeO OMe OMe+

23%

+HO

3%



3-methoxyphenyl ether (36.3 mg, 0.158 mmol), dodecane (internal standard for GC, 45.3


mixture showed the formation of anisole (108 m/z), 3-methoxylphenol (124 m/z),

benzene (78 m/z) and phenol (94 m/z) in 65%, 83%, 23% and 3% yields respectively at

94% conversion of di-3-methoxyphenyl ether.

Hydrogenolysis of di-4-methylphenyl ether (Table 1, Entry 6) O


120 °C, 48 h+

HO20% Ni(COD)2,

97% 99%(1 bar at rt) MeMeMe Me




32

4-methylphenyl ether (30.1 mg, 0.152 mmol), dodecane (internal standard for GC, 48.2



and 99% yields respectively at full conversion of di-4-methylphenyl ether.

Hydrogenolysis of di-4-tert-butylphenyl ether (Table 1, Entry 7) O


120 °C, 48 h+

HO20% Ni(COD)2,

72% 73%(1 bar at rt) tButButBu tBu



4-tert-butylphenyl ether (43.3 mg, 0.153 mmol), dodecane (internal standard for GC) and

m-xylene (0.8 ml) at 120 °C for 48 h. GC and GC/MS analyses of the reaction mixture

showed the formation of tert-butylbenzene (134 m/z) and 4-tert-butylphenol (150 m/z) in

72% and 73% yields respectively at 74% conversion of di-4-tert-butylphenyl ether.

Hydrogenolysis of phenyl 4-trifluoromethylphenyl ether (Table 1, Entry 8) O


100 °C, 16h+HO10% Ni(COD)2,

(1 bar at rt) 64% 99%

+

4%F3C F3C

23%H3C+


1.6⋅10-2 mmol), SIPr⋅HCl 13.4 mg, 3.13⋅10-2 mmol), NaOtBu (40.0 mg, 0.416 mmol),

phenyl 4-trifluoromethylphenyl ether (35.8 mg, 0.150 mmol), dodecane (41 mg, internal

standard for GC) and m-xylene (0.8 ml) at 100 °C for 16 h. GC and GC/MS analyses of

the reaction mixture showed the formation of trifluoromethylbenzene (146 m/z), phenol

(94 m/z) and benzene (78 m/z) in 64%, 99% and 4% yields respectively at full conversion

of 4-trifluoromethylphenyl ether. Toluene (92 m/z) was observed as a side product

(23%).


33

Hydrogenolysis of 4-methoxyphenyl 4-trifluoromethylphenyl ether (Table 1,

Entry 9)

19%Me

+O


100 °C, 16h+HO10% Ni(COD)2,

(1 bar at rt) 68% 92%F3C F3COMe OMe



methoxyphenyl 4-trifluoromethylphenyl ether (40.0 mg, 0.149 mmol), dodecane (internal

standard for GC, 36.0 mg) and m-xylene (0.8 ml) at 100 °C for 16 h. GC and GC/MS

analyses of the reaction mixture showed the formation of trifluoromethylbenzene (146

m/z) and 4-methoxyphenol (124 m/z) in 68% and 92% yields respectively at full

conversion of 4-methoxyphenyl 4-trifluoromethylphenyl ether. Toluene (m/z 92) was

observed as a side product (19%).

Hydrogenolysis of 4-methoxyphenyl phenyl ether (Table 1, Entry 10)

4%OMe

+O


120 °C, 16h+HO20% Ni(COD)2,

(1 bar at rt) 88% 80%OMe OMe

+OH

17% The reaction was conducted according to General Procedure A with Ni(COD)2 (8.6 mg,


methoxyphenyl phenyl ether (30.4 mg, 0.152 mmol), dodecane (internal standard for GC,

44.6 mg) and m-xylene (0.8 ml) at 120 °C for 16 h. GC and GC/MS analyses of the

reaction mixture showed the formation of benzene (78 m/z), 4-methoxyphenol (124 m/z),

phenol (94 m/z) and anisole (108) in 88%, 80%, 17% and 4% yield respectively at full

conversion of 4-methoxyphenyl phenyl ether.


34

Hydrogenolysis of di-2-methylphenyl ether (Table 1, Entry 11)

O+

40% SIPr·HClH2 NaOtBu, m-xylene,

120 °C, 32 h+

HO20% Ni(COD)2,

85% 85%(1 bar at rt)

Me MeMe Me



2-methylphenyl ether (29.6 mg, 0.149 mmol), dodecane (internal standard for GC, 29.



and 85% yields respectively at 85% conversion of di-2-methylphenyl ether.

Hydrogenolysis of 2-n-hexyloxynaphthalene (Table 2, Entry 1)

+20% Ni(COD)2, 40% SIPr·HClH2 NaOtBu, m-xylene,120 °C, 16h(1 bar at rt)

95%

O+ HO

98%



n-hexyloxynaphthalene (33.9 mg, 0.148 mmol), dodecane (internal standard for GC, 36.7


mixture showed the formation of naphthalene (m/z 128) in 95% yield at full conversion

of 2-n-hexyloxynaphthalene. 1,2,3,4-Tetrahydronaphthalene (m/z 132) was detected as a

side product in trace amounts (1%). To quantify by GC and GC/MS the amount of 1-

hexanol formed in the reaction mixture, the alcohol was converted to (n-

hexyloxy)trimethylsilane using the following derivatization protocol. The reaction

mixture after work up was passed through a short plug of anhydrous sodium sulfate and

mixed with MSTFA (N-methy-N-(trimethylsilyl)trifluoroacetamide, 100 µl). The

solution was stirred at 60 °C for 1 h, cooled to room temperature, and analyzed by GC

and GC/MS. This method showed the formation of (n-hexyloxy)trimethylsilane (m/z 159,

[M-Et] +) in 98% yield based on the amount of starting 2-n-hexyloxynaphthalene.


35

Hydrogenolysis of 2-methoxynaphthalene (Table 2, Entry 2)


89%

OMe+ MeOH



methoxynaphthalene (23.5 mg, 0.149 mmol), dodecane (internal standard for GC, 8.9


mixture showed the formation of naphthalene (m/z 128) in 89% yield at 89% conversion

of 2-methoxynaphthalene. Methanol was detected by GC as a second product. A second

run gave naphthalene in 85% yield at 88% conversion.

Hydrogenolysis of 2-methoxynaphthalene in the presence of AlMe3 at 80 °C (Table

2, Entry 3)

+20% Ni(COD)2, 40% SIPr·HClH2 NaOtBu, AlMe3,m-xylene, 80 °C,(1 bar at rt)

98%16h

OMe

The reaction was conducted according to General Procedure B with Ni(COD)2 (8.3 mg,


methoxynaphthalene (23.9 mg, 0.151 mmol), AlMe3 (2M solution in toluene, 75 µl,

0.150 mmol), dodecane (internal standard for GC, 25.8 mg) and m-xylene (0.8 ml) at 80

°C for 16 h. GC and GC/MS analyses of the reaction mixture showed the formation of

naphthalene (m/z 128) in 98% yield at full conversion of 2-methoxynaphthalene.

Hydrogenolysis of 2-methoxynaphthalene in the presence of AlMe3 at 100 °C


95%16h

OMe



methoxynaphthalene (23.9 mg, 0.151 mmol), AlMe3 (2M solution in toluene, 75 µl, 0.15



36

16 h. GC and GC/MS analyses of the reaction mixture showed the formation of

naphthalene (m/z 128) in 95% yield at full conversion of 2-methoxynaphthalene. 2-

methylnaphthalene (m/z 142) was observed as a side product in 3% yield.

Hydrogenolysis of 1-methoxynaphthalene (Table 2, Entry 4)


OMe

72%

+ MeOH



methoxynaphthalene (24.0 mg, 0.152 mmol), dodecane (internal standard for GC, 19.8

mg) and m-xylene (0.8 ml) at 100 °C for 16 h. Toluene was used as a solvent for work

up. GC and GC/MS analyses of the reaction mixture showed the formation of

naphthalene (m/z 128) in 72% yield at 72 % conversion of 1-methoxynaphthalene.

Methanol was detected by GC as a second product. A second run gave 72% of

naphthalene at 72% conversion.

Hydrogenolysis of 1-methoxynaphthalene in the presence of AlMe3 (Table 2, Entry

5)


OMe

99%16h The reaction was conducted according to General Procedure B with Ni(COD)2 (8.1 mg,


methoxynaphthalene (22.9 mg, 0.145 mmol), AlMe3 (2M solution in toluene, 75 µl, 0.15


16 h. GC and GC/MS analyses of the reaction mixture showed the formation of

naphthalene (m/z 128) in 99% yield at full conversion of 1-methoxynaphthalene.


37

Hydrogenolysis of 4-methoxybiphenyl (Table 2, Entry 6)

+20% Ni(COD)2, 40% SIPr·HClH2 NaOtBu, m-xylene,120 °C, 32 h(1 bar at rt)

85%

O+ HO

85%Ph Ph



n-hexyloxybiphenyl (38.3 mg, 0.151 mmol), dodecane (internal standard for GC, 43.0


mixture showed the formation of biphenyl (m/z 154) in 85% yield at 85% conversion of

4-n-hexyloxybiphenyl. The second product, n-hexanol (85%) was detected by GC and

GC/MS after conversion to (n-hexyloxy)trimethylsilane (m/z 159, [M-Et] +) by treatment

of the crude reaction mixture with N-methy-N-(trimethylsilyl)trifluoroacetamide

(MSTFA); see derivatization protocol described in the procedure for the hydrogenolysis

of 2-n-hexyloxynaphthalene on p. 34.

Hydrogenolysis of 4-methoxybiphenyl (Table 2, Entry 7)

+20% Ni(COD)2, 40% SIPr·HClH2 NaOtBu, m-xylene,120 °C, 32 h(1 bar at rt)

59%

OMe

PhPh+ MeOH



methoxybiphenyl (27.9 mg, 0.152 mmol), dodecane (internal standard for GC, 23.4 mg)

and m-xylene (0.8 ml) at 120 °C for 16 h. Toluene was used as a solvent for work up. GC

and GC/MS analyses of the reaction mixture showed the formation of biphenyl (m/z 154)

in 59% yield at 60% conversion of 4-methoxybiphenyl. Methanol was detected as a

second product. A second run gave 57% of biphenyl at 57% conversion.


38

Hydrogenolysis of 4-methoxybiphenyl in the presence of AlMe3 (Table 2, Entry 8) 20% Ni(COD)2, 40% SIPr·HClNaOtBu, AlMe3,m-xylene, 100 °C,

32 h

+ H2(1 bar at rt)

65%

OMe

PhPh



methoxybiphenyl (28.3 mg, 0.154 mmol), AlMe3 (2M solution in toluene, 75 µl, 0.15


16 h. GC and GC/MS analyses of the reaction mixture showed the formation of biphenyl

(m/z 154) in 65% yield at 65% conversion of 4-methoxybiphenyl. A second run

conducted at 120 °C for 32 h gave 62% of biphenyl at 68% conversion.

Hydrogenolysis of 4-tert-butylbenzyl phenyl ether (Table 3, Entry 1)

H2

(1 bar at rt)+ NaOtBu, m-xylene,

120 °C, 16 h

20 mol% SIPr·HCl

99% 93%

10 mol% Ni(COD)2,O

tBu

Me

tBu+

HO



tert-butylbenzyl phenyl ether (36.1 mg, 0.150 mmol), dodecane (internal standard for

GC, 20.4 mg) and m-xylene (0.8 ml) at 100 °C for 16 h. GC and GC/MS analyses of the

reaction mixture showed the formation of 4-tert-butyltoluene (m/z 148) and phenol (m/z

94) in 99% and 93% yields at full conversion of 4-tert-butylbenzyl phenyl ether.

Hydrogenolysis of 4-tert-butylbenzyl methyl ether (Table 3, Entry 2)

+ MeOHH2

(1 bar at rt)+

NaOtBu, m-xylene,120 °C, 16 h

40 mol% SIPr·HCl20 mol% Ni(COD)2,

OMetBu

Me

tBuX



tert-butylbenzyl methyl ether (27.9 mg, 0.157 mmol), dodecane (internal standard for

GC, 25.4 mg) and m-xylene (0.8 ml) at 120 °C for 16 h. GC analysis of the reaction

mixture showed 1% conversion of 4-tert-butylbenzyl methyl ether.


39

Hydrogenolysis of 4-tert-butylbenzyl methyl ether in the presence of AlMe3 (Table 3,

Entry 3)

H2

(1 bar at rt)+


OMetBu

Me

tBuNaOtBu, AlMe3,m-xylene, 120 °C,

32 h 99% The reaction was conducted according to General Procedure B with Ni(COD)2 (8.3 mg,


tert-butylbenzyl methyl ether (27.2 mg, 0.153 mmol), AlMe3 (2M solution in toluene, 75

µl, 0.15 mmol), dodecane (internal standard for GC, 18.2 mg) and m-xylene (0.8 ml) at

120 °C for 32 h. GC analysis of the reaction mixture showed the formation of 4-tert-

butyltoluene (m/z 148) in 99% yield at full conversion of 4-tert-butylbenzyl methyl ether.

Hydrogenolysis of 4-tert-butylbenzyl methyl ether in the presence of AlMe3 and in

the absence of Ni(COD)2

H2

(1 bar at rt)+

40 mol% SIPr·HClOMetBu

Me

tBuNaOtBu, AlMe3,m-xylene, 120 °C,

32 h

X

The reaction was conducted according to General Procedure B with SIPr⋅HCl (26.9 mg,

6.23⋅10-2 mmol), NaOtBu (36.7 mg, 0.382 mmol), 4-tert-butylbenzyl methyl ether (26.3

mg, 0.148 mmol), AlMe3 (2M solution in toluene, 75 µl, 0.15 mmol), dodecane (internal

standard for GC, 33.6 mg) and m-xylene (0.8 ml) at 120 °C for 32 h. GC analysis of the

reaction mixture showed no conversion of 4-tert-butylbenzyl methyl ether.

Hydrogenolysis of 1-methoxy-1-phenylpropane (Table 3, Entry 4)

H2

(1 bar at rt)+



XEt

OMe

Et



methoxy-1-phenylpropane (22.8 mg, 0.152 mmol), dodecane (internal standard for GC,

22.8 mg) and m-xylene (0.8 ml) at 120 °C for 16 h. GC analysis of the reaction mixture

showed no conversion of 1-methoxy-1-phenylpropane.


40

Hydrogenolysis of 1-methoxy-1-phenylpropane in the presence of AlMe3 (Table 3,

Entry 5)

20% Ni(COD)2, 40% SIPr·HClNaOtBu, AlMe3,m-xylene, 120 °C,

16h

H2

(1 bar at rt)+Et

OMe

Et

96% The reaction was conducted according to General Procedure B with Ni(COD)2 (8.6 mg,


methoxy-1-phenylpropane (23.6 mg, 0.157 mmol), AlMe3 (2M solution in toluene, 75 µl,


°C for 16 h. GC analysis of the reaction mixture showed the formation of 1-

propylbenzene (m/z 120) in 96% yield at full conversion of 1-methoxy-1-phenylpropane.

A second run gave 99% of 1-propylbenzene at full conversion of 1-methoxy-1-

phenylpropane.

Hydrogenolysis of bis(m-phenoxyphenyl)benzene (Fig. 3A) O O

+HO

+HO OH

1 equiv. 1.9 equiv. 1.7 equiv.0.3 equiv.

+ H2 NaOtBu, m-xylene,120 °C, 16 h

(1 bar at rt)

Ni(COD)2/SIPr·HCl +HO OPh

0.09 equiv.

O O

The reaction was conducted according to General Procedure A with Ni(COD)2 (11 mg,


bis(m-phenoxyphenyl)benzene (24.7 mg, 5.53⋅10-2 mmol), dodecane (internal standard

for GC, 22.1 mg) and m-xylene (0.8 ml) at 120 °C for 16 h. TLC probe of the reaction

mixture showed full conversion of bis(m-phenoxyphenyl)benzene. GC and GC/MS

analyses of the reaction mixture showed the formation of benzene (1.9 equiv., m/z 78),

1,3-dimethoxybenzene (0.3 equiv., m/z 110), phenol (1.7 equiv., m/z 94) and 3-

phenoxyphenol (0.09 equiv., m/z 186).


41

Hydrogenolysis of Lignin Model Compounds

Hydrogenolysis of di-2-methoxyphenyl ether (Fig. 3B)

O+ H2 +

HO

(1 bar at rt)+

OMeOMe

47% 66% 15%

OMe OMe

40% SIPr·HClNaOtBu, toluene,

120 °C, 16 h

20% Ni(COD)2,



2-methoxyphenyl ether (36.0 mg, 0.156 mmol), dodecane (internal standard for GC, 36.1


mixture showed the formation of anisole (108 m/z), 2-methoxylphenol (124 m/z) and

benzene (78 m/z) in 47%, 66%, and 15% yields respectively at 75% conversion of di-2-

methoxyphenyl ether.

Hydrogenolysis of 2-methoxyphenyl phenyl ether (Fig. 3B)

O+ H2 +

HO

(1 bar at rt)+

OMeOMe

+OH

OMe

63% 68% 22% 19%


120 °C, 16 h

20% Ni(COD)2,



methoxyphenyl phenyl ether (32 mg, 0.160 mmol), dodecane (internal standard for GC,

40.6 mg) and m-xylene (0.8 ml) at 120 °C for 16 h. GC and GC/MS analyses of the

reaction mixture showed the formation of benzene (78 m/z), 2-methoxylphenol (124

m/z), phenol (94 m/z) and anisole (108 m/z) in 63%, 68%, 22% and 19% yields

respectively at 98% conversion of 2-methoxyphenyl phenyl ether.


42

Hydrogenolysis of 3,4-dimethoxybenzyl 2-methoxyphenyl ether (Fig. 3C)

MeO

O H2

(1 bar)

+HO

+MeO

MeO

MeMeO MeO

MeO

99% 99%


80 °C, 16 h

5% Ni(COD)2,



3,4-dimethoxybenzyl 2-methoxyphenyl ether (41.9 mg, 0.153 mmol), dodecane (internal


analyses of the reaction mixture showed the formation of 1,2-dimethoxy-4-

methylbenzene (152 m/z) and 2-methoxylphenol (124 m/z) in 99% yields for both

products at full conversion of 3,4-dimethoxybenzyl 2-methoxyphenyl ether.

Cleavage of 1-(3,4-Dimethoxyphenyl)-2-(2-methoxyphenoxy)-l,3-propanediol with

NaOtBu in the absence of the nickel catalyst (Fig. 3D)

OOMe OH

OMe

OMe

HONaOtBu, toluene,

100 °C, 2 h

OMeOH

89% A 4 ml screw cap vial was charged with NaOtBu (37.5 mg, 0.390 mmol), di-1-(3,4-

dimethoxyphenyl)-2-(2-methoxyphenoxy)-l,3-propanediol (51.7 mg, 0.154 mmol),

dodecane (internal standard for GC, 32.6 mg), toluene (0.8 ml) and a magnetic stir bar.

After stirring for 5 min at room temperature, the reaction mixture was heated to 100 °C

and stirred for 2 h. The resulting red-brown suspension was cooled to room temperature,

diluted with ether (1 ml) and stirred with 1.5 M aqueous HCl (1 ml). The organic layer

was separated and the aqueous layer was extracted with ether (1 ml). The combined

organic layers were subjected to GC and GC/MS analyses, which showed the formation

of 2-methoxylphenol (124 m/z) in 89% yield. LC-MS of the reaction mixture showed the

formation of numerous products in addition to 2-methoxylphenol. Formation of 2-

methoxylphenol was reported for alkaline hydrolysis of this lignin model

compound (25—27).


43

Competition experiments

Selective hydrogenolysis of diphenyl ether in the presence of 4-tert-butylbenzyl

methyl ether (16 h, Fig. 2B)

+ 40% SIPr HClNaOtBu, toluene,

120 °C, 16 h

O+ +

(1 equiv)(1 equiv) (1 bar at rt)

99%Conversions

100% 1%Yields

tBu

20% Ni(COD)2,

+HO

99%

OMe H2

0%

tBu

Me



diphenyl ether (25.2 mg, 0.148 mmol), 4-tert-butylbenzyl methyl ether (26.8 mg, 0.150


16 h. GC analysis of the reaction mixture showed full conversion of diphenyl ether and

formation of benzene and phenol in quantitative yields (99%), whereas 4-tert-butylbenzyl

methyl ether remained unreacted (conversion 1%) and no 4-tert-butyltoluene was

detected.

Selective hydrogenolysis of 2-methoxynaphthalene in the presence 4-tert-butylbenzyl

methyl ether (Fig. 3C)

+ +

(1 equiv)(1 equiv) (1 bar at rt)

86%Conversions

87% 1%Yields

tBu+OMe H2

0%

tBu

MeOMe40% SIPr HCl


20% Ni(COD)2,



methoxynaphthalene (24.0 mg, 0.152 mmol), 4-tert-butylmethoxybenzene (27.2 mg,


°C for 16 h. GC and GC/MS analyses of the reaction mixture showed 87% conversion of

2-methoxynaphthalene (m/z 158) and formation of naphthalene (mz 128) in 86% yield;

only 1% of 4-tert-butylbenzyl methyl ether (m/z 178) was consumed, and no tert-

butyltoluene was detected.


44

The same reaction at 100 °C for 16 h formed naphthalene in 58% yield at 58%

conversion of 2-methoxynaphtalene; no tert-butyltoluene was detected, and the

conversion of 4-tert-butylbenzyl methyl ether was about 1%.

Selective hydrogenolysis of 2-methoxynaphthalene in the presence 4-tert-butylbenzyl

methyl ether and 1 equiv of AlMe3 (Fig. 3C)

+ +

(1 equiv)(1 equiv) (1 bar at rt)Conversions Yields

tBu+OMe H2tBu

MeOMe

97%100% 1% 1%

40% SIPr HCl,


20% Ni(COD)2,

AlMe3 (1 equiv.)



methoxynaphthalene (24.9 mg, 0.157 mmol), 4-tert-butylmethoxybenzene (26.8 mg,

0.150 mmol), AlMe3 (2M solution in toluene, 75 µl, 0.15 mmol), dodecane (internal


analyses of the reaction mixture showed full conversion of 2-methoxynaphthalene and

formation of naphthalene (m/z 128) in 97% yield; 1% of the starting 4-tert-butylbenzyl

methyl ether (m/z 178) was consumed to give tert-butyltoluene (m/z 148) in trace

amounts (1%).

Selective hydrogenolysis of diphenyl ether in the presence of 4-tert-

butylmethoxybenzene (6 h, Fig. 3D)

+ 40% SIPr HClNaOtBu, toluene,

120 °C, 6 h

OMeO+

(1 equiv)(1 equiv) (1 bar at rt)Conversions Yields

tBu

20% Ni(COD)2,

+HO

H2 +tBu

94%100% 5% 94% 2% The reaction was conducted according to General Procedure A with Ni(COD)2 (8.5 mg,


diphenyl ether (25.9 mg, 0.152 mmol), 4-tert-butylmethoxybenzene (24.9 mg, 0.151



45

6 h. GC analysis of the reaction mixture showed full conversion of diphenyl ether and

formation of benzene and phenol in 94% yields; only 5% of the starting 4-tert-

butylbenzyl methyl ether was consumed to give tert-butyltoluene in 2% yield.

Mercury poisoning experiments Hydrogenolysis of diphenyl ether in the presence of excess of mercury.

+O

+

(1 bar at rt)99%

HO

99%

H2

99% 99%no Hg320 equiv. Hg

40% SIPr HClNaOtBu,

120 °C, 16 h

20% Ni(COD)2,

m-xylene,


Ni(COD)2 (8.4 mg, 3.1⋅10-2 mmol), SIPr⋅HCl (27.1 mg, 6.34⋅10-2 mmol), NaOtBu (39.9

mg, 0.415 mmol) and a magnetic stir bar. A solution of diphenyl ether (26.0 mg, 0.153

mmol) and dodecane (internal standard for GC, 21.0 mg) in m-xylene (0.8 ml) were

added. The mixture was stirred for 3 min at which time mercury (1.96 g, 9.77 mmol, 320

equiv. with respect to the catalyst) was added. The Schlenk tube was sealed with the

Teflon stopcock and removed from the glovebox. The reaction mixture was degassed via

two cycles of freeze-pump-thaw, and the tube was pressurized with 1 bar (15 psi) of

hydrogen at room temperature, sealed with the Teflon stopcock, and heated in an oil bath

at 120 °C for 16 h. The reaction mixture was then cooled to room temperature, diluted

with ether (1 ml) and quenched with 1.7M aqueous HCl (1 ml) followed by stirring for 10

min. The organic layer was separated, and the aqueous layer was extracted with 1 ml of

ether. The combined organic layers were passed through a short pad of Celite and

subjected to GC and GC/MS analyses, which showed the formation of benzene (m/z 78)

and phenol (m/z 94) in quantitative yields (99%) at full conversion of the starting

diphenyl ether; no decelerating effect of the added mercury was observed, as compared to

the hydrogenolysis in the absence of mercury (99% yields of benzene and phenol).


46

Hydrogenolysis of 2-methoxynaphthalene in the presence of excess of mercury. 40% SIPr HCl,

100 °C, 16 h

+

(1 bar at rt)

20% Ni(COD)2,

H2

OMe

95%95%

no Hg311 equiv. Hg

AlMe3NaOtBu,m-xylene,


Ni(COD)2 (8.2 mg, 3.0⋅10-2 mmol), SIPr⋅HCl (26.1 mg, 6.11⋅10-2 mmol), NaOtBu (40.6

mg, 0.422 mmol) and a magnetic stir bar. A solution of 2-methoxynaphthalene (25 mg,

0.158 mmol) and dodecane (internal standard for GC, 17.9 mg) in m-xylene (0.8 ml) were

added, and the mixture was stirred for 3 min, followed by addition of AlMe3 (2M

solution in toluene, 75 µl, 0.15 mmol). After stirring for 1 min, mercury (1.86 g, 9.28

mmol, 311 equiv. with respect to the catalyst) was added, and the Schlenk tube was

sealed with the Teflon stopcock and removed form the glovebox. The reaction mixture

was degassed via two cycles of freeze-pump-thaw, and the tube was pressurized with 1

bar (15 psi) of hydrogen at room temperature, sealed with the Teflon stopcock, and

heated in an oil bath at 120 °C for 16-48 h. The reaction mixture was then cooled to room

temperature, diluted with ether (1 ml) and quenched with 1.7 M aqueous HCl (1 ml),

followed by stirring for 10 min. The organic layer was separated, and the aqueous layer

was extracted with 1 ml of ether. The combined organic layers were passed through a

short pad of Celite and subjected to GC and GC/MS analyses, which showed the

formation of naphthalene (m/z 128) in 95% yield at full conversion of the starting 2-

methoxynaphthalene; no decelerating effect of the added mercury was observed, as

compared to the experiment in the absence of mercury (95% yield of naphthalene).


47

Table S3. Selected Results on the Effect of Ligand, Temperature and Amount of Base

on Hydrogenolysis of Diphenyl Ether

+O

+

(1 bar at rt)

HOH2

40% LNaOtBu, m-xylene,

T °C, 16 h

20% Ni(COD)2,

Entry Ligand L NaOtBu, equiv. T, °C Conversion, % Yield of PhH, % Yield of PhOH,

% 1 - 0 120 0 0 0 2 PCy3 0 120 1 1 0 3 PCy3 2.5 120 4 0 0 4 SIPr·HCl 0.44 120 73 72 6 5 SIPr·HCl 2.5 120 100 99 99 6 SIPr·HCl 2.5 100 75 69 75

Conditions: see General Procedure A (p. 29).

Table S4. Effect of Ligand, Nickel Source, Temperature, Amount of Base and AlMe3 on

Hydrogenolysis of 2-Methoxynaphthalene

T °C, 16 h

+

(1 bar at rt)

"Ni", L,H2

OMeAlMe3

NaOtBu,m-xylene,

Entry “Ni” “Ni”, mol % Ligand L NaOtBu,

equiv. AlMe3, equiv. T, °C Conversion, % Yield of

naphthalene, % 1 Ni(COD)2 20 SIPr 0 0 100 24 15 2 Ni(COD)2 20 SIPr·HCl 0.44 0 100 33 29 3 Ni(COD)2 20 SIPr·HCl 2.5 0 100 58 57 4 Ni(COD)2 20 SIPr·HCl 2.5 0 120 89 89 5 Ni(COD)2 20 SIPr·HCl 2.5 1 100 100 95 6 Ni(COD)2 5 SIPr·HCl 2.5 1 100 10 7 7 Ni(COD)2 20 SIPr·HCl 2.5 1 80 100 98 8 Ni(COD)2 20 SIPr·HCl 0.44 1 100 34 17 9 Ni(COD)2 20 SIPr·HCl 2.5 0.2 100 66 66 10 Ni(acac)2 20 SIPr·HCl 2.5 1 100 57 57

Conditions: see General Procedure A and B (p. 29).


48

Table S5. Control Experiments for Hydrogenolyisis of 2-Methoxynaphthalene

OMe+ H2 m-xylene,

100 oC, 16 hNi(COD)2+ + SIPr.HCl + AlMe3+tBuONa

1 bar 0.2 equiv 0.4 equiv 2.5 equiv 1 equiv1 equiv

Entry H2 Ni(COD)2 SIPr.HCl NaOtBu AlMe3 Conversion, % Yield, % 1 + - - + - 3 0 2 + - + + - 5 0 3 + - - + + 5 0 4 + - - - - 4 0 5 + - + + + 4 0 6 + + - + - 2 0 7 - + + + + 2 8* 8 + + + + + 100 98 9 + + + + - 58 57

10 - + + + - 4 4 11 + + - + - 2 0

* 2-Methylnaphthalene was detected by GC/MS as a main product (41%). Procedure: see General Procedures A and B (p. 29).

Table S6. Catalyst Stability Estimation in Hydrogenolysis of Methyl Aryl Ethers.

OMe+

20% Ni(COD)2, 40% SIPr·HClH2

R R

tBuONa, m-xylene(1 bar)

+ MeOH

Entry Aryl Ether Temp, oC Time, h Conversion, % Yield of Arene, %

1 140 16 68 66 2 140 32 68 65

3 120 16 88 84 4

OMe

120 32 89 85

5 120 16 72 71

6

OMe

120 32 72 72

7 120 16 46 42

8 120 32 60 59

9 Ph

OMe

120 48 60 59

Conditions: see General Procedure A (p. 29).


49

7. NMR spectra. Di-2-methoxyphenyl ether. 1H NMR (400 MHz, CDCl3).

Di-2-methoxyphenyl ether. 13C {1H} NMR (100 MHz, CDCl3).

OOMe OMe

OOMe OMe


50

2-Methoxyphenyl phenyl ether. 1H NMR (400 MHz, CDCl3).

2-Methoxyphenyl phenyl ether. 13C {1H} NMR (125 MHz, CDCl3).

OOMe

OOMe


51

Di-3-methoxyphenyl ether. 1H NMR (400 MHz, CDCl3).

Di-3-methoxyphenyl ether. 13C {1H} NMR (100 MHz, CDCl3).

OMeO OMe

OMeO OMe


52

Di-4-tert-butylphenyl ether. 1H NMR (400 MHz, CDCl3).

Di-4-tert-butylphenyl ether. 13C {1H} NMR (125 MHz, CDCl3).

O

tButBu

O

tButBu


53

Di-3-methylphenyl ether. 1H NMR (400 MHz, CDCl3).

Di-3-methylphenyl ether. 13C {1H} NMR (100 MHz, CDCl3).

OMe Me

OMe Me


54

4-Methoxyphenyl 4-trifluoromethylphenyl ether. 1H NMR (500 MHz, CDCl3).

4-Methoxyphenyl 4-trifluoromethylphenyl ether. 19F {1H} NMR (470 MHz, CDCl3).

O

F3C OMe

O

F3C OMe


55

4-Methoxyphenyl 4-trifluoromethylphenyl ether. 13C {1H} NMR (125 MHz, CDCl3).

O

F3C OMe


56

Di-2-Methylphenyl ether. 1H NMR (400 MHz, CDCl3).

Di-2-Methylphenyl ether. 13C {1H} NMR (100 MHz, CDCl3).

OMe Me

OMe Me


57

4-Methylphenyl phenyl ether. 1H NMR (400 MHz, CDCl3).

4-Methylphenyl phenyl ether. 13C {1H} NMR (100 MHz, CDCl3).

O

OMe

O

OMe


58

2-(Hexyloxy)naphthalene. 1H NMR (400 MHz, CDCl3).

2-(Hexyloxy)naphthalene. 13C {1H} NMR (100 MHz, CDCl3).

O

O


59

4-(Hexyloxy)biphenyl. 1H NMR (400 MHz, CDCl3).

4-(Hexyloxy)biphenyl. 13C {1H} NMR (100 MHz, CDCl3).

O

O


60

4-tert-Butylbenzyl phenyl ether. 1H NMR (400 MHz, CDCl3).

4-tert-Butylbenzyl phenyl ether. 13C {1H} NMR (100 MHz, CDCl3).

OtBu

OtBu


61

3,4-Dimethoxybenzyl 2-methoxyphenyl ether. 1H NMR (500 MHz, CDCl3).

3,4-Dimethoxybenzyl 2-methoxyphenyl ether. 13C {1H} NMR (125 MHz, CDCl3).

O

MeOOMe

MeO

O

MeOOMe

MeO


62

1-Methoxy-1-phenylpropane. 1H NMR (400 MHz, CDCl3).

1-Methoxy-1-phenylpropane. 13C {1H} NMR (100 MHz, CDCl3).

OMe

OMe


63

Methyl 4-tert-butylbenzyl ether. 1H NMR (500 MHz, CDCl3).

Methyl 4-tert-butylbenzyl ether. 13C {1H} NMR (125 MHz, CDCl3).

OMetBu

OMetBu


64

Methyl 2-(2-methoxyphenoxy)acetate. 1H NMR (400 MHz, CDCl3).

Methyl 2-(2-methoxyphenoxy)acetate. 13C {1H} NMR (100 MHz, CDCl3).

O

OMe

OMe

O

O

OMe

OMe

O


65

Methyl 3-(3,4-dimethoxyphenyl)-3-hydroxy-2-(2-methoxyphenoxy)propanoate. 1H NMR (500 MHz, CDCl3).

Methyl 3-(3,4-dimethoxyphenyl)-3-hydroxy-2-(2-methoxyphenoxy)propanoate. 13C {1H} NMR (125 MHz, CDCl3).

OOMe OH

MeO O OMe

OMe

OOMe OH

MeO O OMe

OMe


66

1-(3,4-Dimethoxyphenyl)-2-(2-methoxyphenoxy)-l,3-propanediol. 1H NMR (500 MHz, CDCl3).

1-(3,4-Dimethoxyphenyl)-2-(2-methoxyphenoxy)-l,3-propanediol. 13C {1H} NMR (125 MHz, CDCl3).

OOMe OH

OMe

OMe

HO

OOMe OH

OMe

OMe

HO


67

8. References.

S1. J. E. Thomson, C. D. Campbell, C. Concellón, N. Duguet, K. Rix, A. M. Z. Slawin,

A. D. Smith, J. Org. Chem. 73, 2784 (2008).

S2. S. Gaillard, X. Bantreil, A. M. Slawin, S. P. Nolan, Dalton Trans. 6967 (2009).

S3. D. Maiti, S. L. Buchwald, J. Org. Chem. 75, 1791 (2010).

S4. A. D. Sagar, R. H. Tale, R. N. Adude, Tetrahedron Lett. 44, 7061 (2003).

S5. A. B. Nadu, E. A. Jaseer, G. Sekar, J. Org. Chem. 74, 3675 (2009).

S6. K. W. Anerson, T. Ikawa, R. E. Tundel, S. L. Buchwald, J. Am. Chem. Soc. 128,

10694 (2006).

S7. G. Chen, A. S. C. Chan, F. Y. Kwong, Tetrahedron Lett. 48, 473 (2007).

S8. O. Schickh, Ber. Deutsch. Chem. Gessell. B 69B, 242 (1936).

S9. J. B. Chazan, G. Ourisson, Bull. Soc. Chim. Fr. 1484 (1968).

S10. U. Masahiro, C. Hori, K. Suzawa, M. Ebisawa, Y. Kondo, Eur. J. Chem. 1965

(2005).

S11. H.-J. Cristau, P. P. Cellier, S. Hamada, J.-F. Spindler, M. Taillefer Org. Lett. 6, 913

(2004).

S12. A. R. Katritzky, A. Saba, R. C. Patel, J. Chem. Soc. Perkin Trans. I 1492 (1981).

S13. T. Ruhland, K. Andersen, H. Pedersen, J. Org. Chem. 63, 9204 (1998).

S14. H. Mikawa, Bull. Soc. Chem. Jpn. 27, 53 (1954).

S15. F. Alonso, P. Riente, M. Yus, Eur. J. Chem. 6304 (2009).

S16. D. R. Dimmel, W. Y. Fu, S. B. Gharpure, J. Org. Chem. 41, 3092 (1976).

S17. I. Barba, M. Tornero, Tetrahedron 48, 9967 (1992).

S18. K. Lundquist, S. Remmerth, Acta Chem. Scand. B 29, 276 (1975).

S19. I. Berndtsson, K. Lundquist, Acta Chem. Scand. B 31, 725 (1977).

S20. T. Ahvonen, G. Brunow, P. Kristersson, K. Lundquist, Acta Chem. Scand. B 37,

845 (1983).

S21. S. Ciofi-Baffoni, L. Banci, A. Brandi, J. Chem. Soc. Perkin Trans. 1, 3207 (1998).

S22. E. Baciocchi, C. Fabbri, O. Lanzalunga, J. Org. Chem. 68, 9061 (2003).

S23. S. Son, F. D. Toste, Angew. Chem. Int. Ed. 49, 3791 (2010).


68

S24. J. Myska, V. Ettel, M. Bomar, Coll. Czech. Chem. Comm. 26, 902 (1961).

S25. Miksche, G. Acta Chem. Scand. 27, 1355 (1973).

S26. K. Poppius, Acta Chem. Scand. B 38, 611 (1984).

S27. D. R. Dimmel, D. Shepard, L. F. Perry, J. Wood Sci. Tech. 5, 229 (1985).

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Selective, Nickel-Catalyzed Hydrogenolysis of Aryl Ethers · Selective, Nickel-Catalyzed Hydrogenolysis of Aryl Ethers. Supporting Online Material. 4 a final temperature of 300 °C,