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Carl Trudel, Literature MeetingWednesday, April 11th 2012
Fe SeN
O
2
Pd SePhPhSe
Cl
Singh, F. V.; Wirth, T. In Organoselenium Chemistry; Wiley-VCH Verlag GmbH & Co. KGaA, 2012, p 321-360.
Alberto, E. E.; Braga, A. L.; Woollins, J. D.; Laitinen, R. In Selenium and Tellurium Chemistry; Springer Berlin Heidelberg, 2011, p 251-283.
2
About this presentation
3
About Me
Presentation ScheduleSome selenium facts
Stoichiometric reactionsSelenium as a catalyst
CarbonylationOxidation (B.-V., epoxidation, selenylation-
deselenylation, alkyne, allylic, alcohol, imine, aniline...)
HalobromationGPx like activityAlkylation
Selenium as a ligand forCopperPalladium
4
Fun FactsDiscovered by J. J. Berzelius in 1817.
Selenium => Selene (moon)Chalcogen (O, S, Te)Among the 25 least common elements
0.05 – 0.09 ppm in the earth crustRecommended daily intake: 55µg (max
400µg/day)>1000µg/day => intoxicationsBrazil nuts, fishes and seafood (oyster and
tuna)...North American cereals (Beer!)
5
Berzelius, J. J. Afhandl. Fys. Kemi Mineralogi. 1818, 42.Alberto, E. E.; Braga, A. L.; Woollins, J. D.; Laitinen, R. In Selenium and Tellurium Chemistry; Springer Berlin Heidelberg, 2011, p 285-302.http://www.passeportsante.net/fr/Solutions/PlantesSupplements/Fiche.aspx?doc=selenium_ps [April 2012]
Other Facts and NomenclatureUsed in everyday
applications Glass-making, electronics,
printers, solar cellsGlutathione peroxidase
enzymes and selenoproteinesAntioxidants, antitumor,
antimicrobial, antiviral
Se(s) 44.84 $/mol SeO2 54.59 $/molPh2Se 4 768.33 $/mol (PhSe)2 3 970,29 $/mol[mCPBA 120.11 $/mol]
6
Selenols RSeH
Selenides RSeR'
Diselenides RSeSeR'
Selenyl halides RSeX
Selenoxides RSe(O)R'
Selenonium/ate RR'R''Se+/-
Selenones RSe(O)2R'
Selenones RSe(O)2R'
Selenenic acid RSeOH
Seleninic acid RSe(O)OH
Perseleninic acid RSe(O)OOH
www. sigmaaldrich.com [april 2012]
Me3Si
Se2
NMe2
Soichiometric Selenium Chemistry
7
Br 1) Mg, Et2O
2) Se,
Se
3) Br2
2
64 - 70%
Reich, H. J.; Cohen, M. L.; Clark, P. S. Org. Synth. 1988, 50-9, 533-537.
Santi, C.; Wirth, T. Tetrahedron: Asymm. 1999, 10, 1019-1023.
Thompson, D. P.; Boudjouk, P. J. Org. Chem. 1988, 53, 2109-2112.
M(S) + Se(S) MSeSeMNaphtalene (cat)
THF
Carbonylation of aminoalcohols
8
1st Selenium Catalyzed Reaction
R'' XH
R NR'HR
Se (5 mol%)
DMF (1.4 M)
Et3N (1 equiv)
O2/CO (15 %V/V)R'' X
H
R NR
O
R'
X = O, S 64 - 99%
Sonoda, N.; Yamamoto, G.; Natsukawa, K.; Kondo, K.; Murai, S. Tetrahedron Lett. 1975, 16, 1969-1972.
HONH2
Se + Et3N
HSe- Et3NH+½ O2
H2O
HONH
CO +
Se-
O
Et3NH+
NH
O-Se
HO
Et3NH+
ONH
O
Perseleninic acid
Hydroxy Perhydroxy Selenane
9
Selenium Based Oxygen Transfer Reagents
PhSe
SePh 3 H2O2
2 H2O
PhSe
OH
O2
3 H2O2
PhSe
OOH
O2 + 2 H2O
PhSe
PhPh
SePh
O
PhSe
Ph
[O] H2O HOOH
PhSe
Ph
H2O2HO
OOH+ H2O
ClCl
NO
SO2Ph ArSe+
R
O-
Up to 95% ee
Up to 90% yld.
Davis, F. A.; Reddy, R. T. J. Org. Chem. 1992, 57, 2599-2606.
ArSe+
R
O- ArSe
OH
ROH
ArSe+
O-
RH2O H2O
10
Baeyer-Villiger Reaction
Alberto, E. E.; Braga, A. L.; Woollins, J. D.; Laitinen, R. In Selenium and Tellurium Chemistry; Springer Berlin Heidelberg, 2011, p 251-283.
O
O
O
H
Ar
R1 R2
O
Ar O
O
O R2
OH
R1
R1 O
O
R2
Ar OH
O+
O
SeO
O
H
Ar
R1 R2
O
ArSe
O
O
O R2
OH
R1
R1 O
O
R2
ArSe
OH
O+
11
Baeyer-Villiger Reaction, Perseleninic Acids
Alberto, E. E.; Braga, A. L.; Woollins, J. D.; Laitinen, R. In Selenium and Tellurium Chemistry; Springer Berlin Heidelberg, 2011, p 251-283.
PhSe
SePh 3 H2O2
2 H2O
PhSe
OH
O2
3 H2O2
PhSe
OOH
O2 + 2 H2O
12
Catalytic Baeyer-Villiger Reaction
Alberto, E. E.; Braga, A. L.; Woollins, J. D.; Laitinen, R. In Selenium and Tellurium Chemistry; Springer Berlin Heidelberg, 2011, p 251-283.
ArSe
OH
O
O
SeO
O
H
Ar
H2O2
H2O
R1 R2
O
ArSe
O
O
O R2
OH
R1
R1 O
O
R2
13
Catalytic Baeyer-Villiger Reaction
ten Brink, G.-J.; Vis, J.-M.; Arends, I. W. C. E.; Sheldon, R. A. J. Org. Chem. 2001, 66, 2429.
ArSe
O
O
O R2
O
R1
H
2O Se
(1 mol%)
Ar
60% H2O2 (2 equiv)CF3CH2OH (1M)
20 °C, 4 h
O
O
2
21%
Se
CF3
2
62%
Se
CF3
F3C 2
45%
SeF3C 2
40%
Se
F3C
91%95% 87% 81%
Conversion
Selectivity
2
19%
Se
NO2
2
37%
Se 2
31%
SeO2N 2
30%
Se
O2N
95%75% 93% 90%
C3° > C2° > Bn > Ar/H* > C1° > Me
CF3CH2OH, 20 °CHydrolysis might be an issueImportant substituent effect 14
Catalytic Baeyer-Villiger Reaction
ten Brink, G.-J.; Vis, J.-M.; Arends, I. W. C. E.; Sheldon, R. A. J. Org. Chem. 2001, 66, 2429.
ArSe
OH
O
O
SeO
O
H
Ar
H2O2
H2O
R1 R2
O
ArSe
O
O
O R2
OH
R1
R1 O
O
R2
2Se
CF3
F3C
Pioneer work by Sharpless
15
Seleninic Acid Epoxidation
Hori, T.; Sharpless, K. B. J. Org. Chem. 1978, 43, 1689-1697.
PhSe
OH
O
PhSe
2+ Ph
SeOHH2O + 3
DCM, MgSO4
OH
SePh
TBHP
(2 equiv)
OH
OH
O
OH
SePh
HO
H2O2
O
(10 mol% cat)
Pioneer work by Sharpless
16
Seleninic Acid Epoxidation
Hori, T.; Sharpless, K. B. J. Org. Chem. 1978, 43, 1689-1697.
PhSe
OH
O
PhSe
2+ Ph
SeOHH2O + 3
DCM, MgSO4
OH
SePh
TBHP
(2 equiv)
OH
OH
O
OH
SePh
HO
SeOH
O
NO2O2N
OHO
OHO
+
3:2
+
~2:1
OH
O
OHO
DCM or trifluoroethanol
Recyclable perfluorinated solvent
30 % H2O2 causes emulsions
DihydroxylationNaOAc increase yields
17
Seleninic Acid Epoxidation
Betzemeier, B.; Lhermitte, F.; Knochel, P. Synlett 1999, 489. Alberto, E. E.; Braga, A. L.; Woollins, J. D.; Laitinen, R. In Selenium and Tellurium Chemistry; Springer Berlin Heidelberg, 2011, p 251-283.
C8F17 C8F17
Se nBu
R (5 mol%)
60% H2O2 (1.5 - 2 equiv)C8F7Br / Benzene
70 °C, 1 - 12 h
R
O
63 - 97 %
O
SeO
O
H
Ar
18
Seleninic Acid Dihydroxylation
Santoro, S.; Santi, C.; Sabatini, M.; Testaferri, L.; Tiecco, M. Adv. Synth. Catal. 2008, 350, 2881-2884.
Sheldon, R. A. et al. J. Chem. Soc., Perkin Trans. 1 2001, 224.
60% H2O2 (2 equiv)F3CCH2OH, NaOAc (0.2 mol%)
20 °C, 1 h
O(0.25 mol%)
SeOH
O
F3C
CF3
98%
6% H2O2 / MeCN23 °C, 24 h
(10 mol%)
Se
76%99:1 (syn:anti)
2
OH
OH
6% H2O2 / MeCN24 h, -10 °C
Se
92% ee
2
Ph
S
(0.5 equiv)
Ph OHOH
56%, 68:32 (syn:anti)
HO PhOH
+
19
Sequential Selenylation-Desenylation
Santi, C. Et al. Chem. Eur. J. 2002, i, 1118. Freudendahl, D. M.; Santoro, S.; Shahzad, S. A.; Santi, C.; Wirth, T. Angew. Chem. Int. Ed. 2009, 48, 8409.
OMe
S
Se2
R1
R2
R1
R2
(NH4)2S2O8
Nuc(NH4)2S2O8
Nuc
R3
R1
R2
R1
R2
R3
Nuc
SeAr*
Nuc
SeAr*
*
Ph3SnHAIBN
Toluene,
R1
R2 Nuc
Up to 98% ee
H2O2,MeOH
R1
R2 Nuc
Up to 96% ee
R3
20
Sequential Selenylation-Desenylation
Santi, C. Et al. Chem. Eur. J. 2002, i, 1118. Freudendahl, D. M.; Santoro, S.; Shahzad, S. A.; Santi, C.; Wirth, T. Angew. Chem. Int. Ed. 2009, 48, 8409.
OMe
S
Se2
R1 R2
*ArSe
2½ + ½ (NH4)2S2O8 *Ar SeOSO3-
Nuc
R1 R2
Se+
*ArNH4
+
R1 R2
Nuc
Se*Ar
(NH4)2S2O8
R1 R2
Nuc
21
Sequential Selenylation-Desenylation
Santi, C. Et al. Chem. Eur. J. 2002, i, 1118. Freudendahl, D. M.; Santoro, S.; Shahzad, S. A.; Santi, C.; Wirth, T. Angew. Chem. Int. Ed. 2009, 48, 8409.
CO2H -30 48 85 55O
O
CO2Me 20 68 98 68MeOHCO2Me
OMe
Ph CO2Me 20 48 98 78MeOHPh CO2Me
OMe
Ph CO2Me 20 96 98 82MeCN/H2OPh CO2Me
OMe
DCM
Starting alkene T (°C) Time (h) Yield (%) ee (%)Solvent
R2(2.5 mol%)
R1
OMe
S
Se2
(NH4)2S2O8R2R1
Nuc
Nuc
22
Alkyne Oxidation
Santoro, S.; Battistelli, B.; Gjoka, B.; Si, C.-w. S.; Testaferri, L.; Tiecco, M.; Santi, C. Synlett, 2010, 1402.
R2(Cat.)
R1
Se2
(NH4)2S2O8R2R1
H2O/MeCN
OH
R2 (Cat.)
R1
Se2
(NH4)2S2O8
H2O/MeCN
R2R1
O
O
23
Alkyne Oxidation
Santoro, S.; Battistelli, B.; Gjoka, B.; Si, C.-w. S.; Testaferri, L.; Tiecco, M.; Santi, C. Synlett, 2010, 1402.
R1
R2
PhSe
2½ + ½ (NH4)2S2O8 Ph SeOSO3H
R1 R2
O
Se+
Ph
H2O
R1 R2
O
H2O
R1 R2
OH
SePh
OH
R1 R2
O
SePh
(NH4)2S2O8
OSO3-
R1 R2
O
O
24
Alkyne Oxidation
Santoro, S.; Battistelli, B.; Gjoka, B.; Si, C.-w. S.; Testaferri, L.; Tiecco, M.; Santi, C. Synlett, 2010, 1402.
R2(10 mol%)
R1
Se2
(NH4)2S2O8 (3 equiv)R2
R1
H2O/MeCN
O
O
60 °C, 24 - 72 h
MePh
O
O
75%
nPrPh
O
O
77%
Ph
O
O
59%
PhPh
O
O
67%
nPrnPr
O
O
67%
MenOct
O
O
57%
OHAr
O
OR
55 - 65%
ROH / DCM
SiO2
Ar
O
O
25
Alcohol Oxidation
van der Toorn, J. C.; Kemperman, G.; Sheldon, R. A.; Arends, I. W. C. E. J. Org.Chem. 2009, 74, 3085.
PhSe
O
O
SePh
O
PhSe
SePh + 3 TBHP
PhSe
OH
O
PhSe
O
O H
R
R
O
PhSeOH
TBHP
tBuOH+
H2OR
OH
SeO
O
Se
O
R
OH
PhSe
OH
O
SeO
O H
R
R
O+ PhSeOH
Excess of TBHP is to be avoided
Presence of water decrease the selectivity
Preactivation of the catalyst shortens reaction time
26
Alcohol Oxidation
van der Toorn, J. C.; Kemperman, G.; Sheldon, R. A.; Arends, I. W. C. E. J. Org.Chem. 2009, 74, 3085.
27
Alcohol Oxidation
van der Toorn, J. C.; Kemperman, G.; Sheldon, R. A.; Arends, I. W. C. E. J. Org.Chem. 2009, 74, 3085.
PhSe
O
O
SePh
O
PhSe
SePh + 3 TBHP
PhSe
OH
O
PhSe
O
O H
R
R
O
PhSeOH
TBHP
tBuOH+
H2OR
OH
SeO
O
Se
O
R
OH
PhSe
OH
O
SeO
O H
R
R
O+ PhSeOH
28
Alcohol Oxidation
Ehara, H.; Noguchi, M.; Sayama, S.; Onami, T. J. Chem. Soc., Perkin Trans. 1 2000, 1429.
Se2
N
R1 R2
OH
SO
ONClNa
Cl
Se
N
O
N SO2 Ar
R2
H
R1
Se
N
HN
O2S Ar
R1 R2
O
SO
ONClNa
Cl
Se
N
HNN SO2 Ar
O2S Ar
O
nHex
99%
O
Ph
99%
O
92%
O
8
24%
29
Allylic Oxidation of Alkene
Crich, D.; Zou, Y. Org. Lett. 2004, 6, 775-777.
R2(10 mol%)
R1Oxidant R2R1
Solvent,
RSe
OH
O
O SeO2H
F5
N SeO2H
O
Iodoxybenzene (H2O2 less selective)Electron-rich alkenes preferentiallyStable catalystDiselenide is recovered after
Na2S2O5 quench(86 - 92%)
30
Allylic Oxidation of Alkene
Crich, D.; Zou, Y. Org. Lett. 2004, 6, 775-777.
R2(10 mol%)
R1PhIO2 (3 equiv) R2R1
PhCF3,
O
SeO2H
F17
41 - 65 %
BzO
Me
BzO
Me
65 %O
Me
Me
H
H
H H
H H
R1 R2RF Se
R1 R2
R1 R2
Se
O
X
SeOHRF
X
HX
ORF
R1 R2
OSe
RF
PhIO2
R1 R2
O
31
Allylic Oxidation of Alkene
Crich, D.; Zou, Y. Org. Lett. 2004, 6, 775-777. Smith, M. B. Organic Synthesis; McGraw-Hill: Boston, MA, 2002; pp. 273-275.
R1 R2
OSe
RFX
H
Oxidation on the more highly substituted side
Endocyclic oxidation for 1-substituted cyclohexene
krel: CH2 > CH3 > CH
Follows Bredt’s rule
O
OAc
50%
Ph
O
63%OHC
62%
32
Imine Oxidation, Catalytic Hydroxylation
Brodsky, B. H.; Du Bois, J. J. Am. Chem. Soc. 2005, 127, 15391.
Cl
NSO2
O
F3C
Cl
NSO2
O
F3C O
Sred
SOox
OH
H
63% 36%
PivOMe
OH
43%
Me
BzO
OHMe
OH
80%
F3C
F3C
SeO
O OH
F3C
F3C
SeO
OH
H2O2
H2O
33
Aniline Oxidation
Priewisch, B.; Rück-Braun, K. J. Org. Chem. 2005, 70, 2350-2352.Zhao, D.; Johansson, M.; Bäckvall, J.-E. Eur. J. Org. Chem. 2007, 4431.
Ar NH2
[O]Ar NHOH
[O]Ar NO
[O]
Ar NN Ar
Ar N+N Ar
O-
Ar NO2
Ar N+
N+ Ar
O-
-O
R
NH2 PhSe
2
(5 mol%)
35% H2O2 (2.2 equiv)CHCl3, r.t., 2 h
R
N
O
75 - 95 %6:1 - >30:1 selectivity
(1.2 - 2 equiv)
35% H2O2 (2.2 equiv)CHCl3, r.t., 2 h
R
N
45 - 72 %1:1 - >99:1 isomer ratio
R3
R2R1
OR2
R3
R1
Br2, Br3+, HOBr
Seleninic acid electron rich reacts faster
34
Oxidation of Bromide Salts
Alberto, E. E.; Braga, A. L.; Woollins, J. D.; Laitinen, R. In Selenium and Tellurium Chemistry; Springer Berlin Heidelberg, 2011, p 251-283.
Br + H2O2 Br +
Br +
2 OH
H2O2 Br + O2 + 2 H
2 H2O2 O2 + 2 H2O
Unknown brominating speciesElectron donating group acceleration
35
Oxidation of Bromide Salts, Seleninic Acids
Alberto, E. E.; Braga, A. L.; Woollins, J. D.; Laitinen, R. In Selenium and Tellurium Chemistry; Springer Berlin Heidelberg, 2011, p 251-283.
O
SeO
O
H
Ar
Br
Br
O
SeOAr
OBr
H
O
SeOAr
OH
Br
HOBr
O
SeO
BrAr
36
Oxidation of Bromide Salts, Selenoxide
Goodman, M. A.; Detty, M. R. Organomet. 2004, 23, 3016.
RSe+
O-
R'
RSe
OH
R'
OH
RSe+
OH
R'
H2O2
RSe
OH
R'
OOHSe
NMe2
O
Ph
RSe+
O-
R'
H2O2 +
RSe
OH
R'
OOH
RSe
OH
R'
OBr
Br-
OH-
Br-OH-Br2 +
Br-HOBr+
OH-
37
Oxidation of Bromide Salts, Seleninic Acid
Drake, M. D.; Bateman, M. A.; Detty, M. R. Organomet. 2003, 22, 4158.
R
OH
O
nO
Br
O
n
R
OHn O
Brn
R
R
SubstratePhSeO2H (10 mol%)
Et2O / 1M NaBr/H2O2
pH 6
Brominated species
EDG
Br
EDG
R
OH
O
n
R
OHn
Br
Br
Br
Br
EDG
Br
Gluthathione peroxidase (GPx)Selenoenzyme (L-
selenocysteine)Reactive oxygen speciesNeurodegenerative disease
(Parkinson, Alzheimer), physiological and inflammatory processes.
Chalcogen-based catalytic antioxidants
38
Disulfide Formation
Alberto, E. E.; Braga, A. L.; Woollins, J. D.; Laitinen, R. In Selenium and Tellurium Chemistry; Springer Berlin Heidelberg, 2011, p 251-283.
HSeCO2H
NH2
L-Selenocysteine
HO NH
O OHN
O
OH
OSH
NH2
Glutathione (SGH)
39
GPx Activity
Alberto, E. E.; Braga, A. L.; Woollins, J. D.; Laitinen, R. In Selenium and Tellurium Chemistry; Springer Berlin Heidelberg, 2011, p 251-283.
HSeCO2H
NH2
L-Selenocysteine
HO NH
O OHN
O
OH
OSH
NH2
Glutathione (SGH)
GPx SeH
ROOH
ROH
GPx SeOH
GSHH2O
GPx SeSG
GSH
GSSG
40
Catlytic Reduction of Enones
Tian, F.; Lu, S. Synlett 2004, 1953.
R
O
Ar R'SeH R
O
Ar
SeR'
R
O
Ar
Se
CO+
H2O
CO2
H2Se R
O
Ar
R
O
Ar
SeH
R
O
Ar
R
O
Ar
Se (20 mol%)CO (0.1 mPa)
H2O/DMF90 °C, 2 - 4 h
76 - 99 %
41
Catalytic Disulfide Formation
Alberto, E. E.; Braga, A. L.; Woollins, J. D.; Laitinen, R. In Selenium and Tellurium Chemistry; Springer Berlin Heidelberg, 2011, p 251-283.
RSeH
RSeOH Se
RSeO2H
SR'
R
H2O
H2O2
H2O
H2O2
R'SH H2O
R'SH
R'S
2
R'SH
R'S
2
3
+ 2 H2O
SeNH
O
Se
HO
Se
HOOH
OSe
O
Diethyl Zinc Addition to Aldehydes
42
Santi, C.; Wirth, T. Tetrahedron: Asym. 1999, 10, 1019-1023. Wirth, T. Tetrahedron Lett. 1995, 36, 7849-7852.
H
O
+ Et2ZnCatalyst
OH
*
Se
Me
N
2
(S)-ROH 91%98%ee
Se
Me
N
2
(S)-ROH 57%91%ee
Se
Me
N
2
(S)-ROH 70%91%ee
Se
Me
N
2
(S)-ROH 78%41%ee
O2N
Se
N
2
(S)-ROH 95%91%ee
Se
Me
N
2
(S)-ROH 98%96%ee
TMS
Diethyl Zinc Addition to Aldehydes
43
Santi, C.; Wirth, T. Tetrahedron: Asym. 1999, 10, 1019-1023. Wirth, T. Tetrahedron Lett. 1995, 36, 7849-7852.
H
O
+ Et2ZnCatalyst
OH
*
Se
Me
N
2
(S)-ROH 91%98%ee
Se
Me
N
2
(S)-ROH 57%91%ee
Se
Me
N
2
(S)-ROH 70%91%ee
Se
N
2
(S)-ROH 95%91%ee
Se
Me
N
2
(S)-ROH 98%96%ee
TMS
OH
OMe
93%, 95%ee
80%, 95%ee
OH
93%, >99%ee
75%, >99%ee
MeO
N
OH
85%, 91%ee
78%, 98%ee
Diethyl Zinc Addition to Aldehydes
44
Braga, A. L.; Galetto, F. Z.; Rodrigues, O. E. D.; Silveira, C. C.; Paixão, M. W. Chirality 2008, 20, 839-845.
H
O
+ Et2ZnCatalyst
OH
*
RSe
NHBoc
2
(R)-ROH 70 - 91%
up to 95%ee
RS
NHBoc
2
(R)-ROH 70 - 90%
up to 95%ee
OH
63%, >99%ee
51%, 70%ee
3
OH
56%, 45%ee
54%, >99%ee
7
Ph
O
Ph
O
Ph Ph
O
OMe
Ph
O
Br
O
Ph
MeO
O
Ph
Br
99%, 96% ee 97%, 95% ee
98%, 96% ee 87%, 97% ee98%, 96% ee 95%, 96% ee
Diethyl Zinc Addition to Enones
45
Shi, M.; Wang, C.-J.; Zhang, W. Chem. Eur. J. 2004, 10, 5507-5516.
NH
NH
Et
PX
PhPh
X = Se, S
1) Cu(MeCN)4BF4 (3 mol%), Ligand (6 mol%)
2) Et2Zn, PhMe, 10 - 20 min
O O
O
60%, 91% ee
O
95%, 90% ee
O
94%, 93% ee
Diethyl Zinc Addition to Enones
46
Shi, M.; Wang, C.-J.; Zhang, W. Chem. Eur. J. 2004, 10, 5507-5516.
NH
NH
Et
PX
PhPh
X = Se, S
O
Cu
Se
R
PPh2
N
NZn
R
* H
Et
LCu
X
L*
LCu
R
L*
LCu
R
L*
O
ZnXR
+ RZnX
R2Zn
ORZn
R
Malonate Alkylation
47
Braga, A. L.; Galetto, F. Z.; Rodrigues, O. E. D.; Silveira, C. C.; Paixão, M. W. Chirality 2008, 20, 839.
O N
R
Ar
TMsCl, THF, 30 min
R'SeSeR'/NaBH4, THF/EtOHReflux, 24 h
SeR
HN
R'
O
Ar
Y
HN
Ph
O
Ph
Pd(3-C3H5)Cl2 (2.5 mol%)Ligand (5 mol%)
BSA, KOAcDCM, 24 h, r.t.
Y = SeS .
Ph Ph
Ph Ph
CO2R'R'O2CR
Malonate Alkylation
48
Braga, A. L.; Galetto, F. Z.; Rodrigues, O. E. D.; Silveira, C. C.; Paixão, M. W. Chirality 2008, 20, 839.
Y
HN
Ph
O
Ph
Pd(3-C3H5)Cl2 (2.5 mol%)Ligand (5 mol%)
BSA, KOAcDCM, 24 h, r.t.
Y = SeS .
Ph Ph
Ph Ph
CO2R'R'O2CR
Se
PdN
Ph
PhO
Ph
Ph
Nuc
Se
PdN
Ph
PhONuc Ph
Ph
Ph Ph
CO2MeMeO2C
SeS .
97%, 98% ee94%, 86% ee
Ph Ph
CO2EtEtO2C
SeS .
95%, 93% ee89%, 84% ee
Ph Ph
CO2EtEtO2C
SeS .
83%, 69% ee61%, 48% ee
Ph Ph
CO2EtEtO2C
SeS .
89%, 82% ee68%, 66% ee
Et Ph
ConclusionSelenium compounds are very versatile catalystsDifferent oxidation state allows completely
different reaction pathwaysLittle work as been focusing on their strong
electron donating properties as a ligandLittle success in achieving stereoselective
reactions with catalytic amount of enantioenriched organoselenium
Developpement towards its industrial use rather than fine chemistry
49
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