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SYNAPS July 2011 -The Biological Roles of Carbohydrates - Glycosylation Methods: O-, C-, N- Glycosylation; 2-deoxy Glycosides - Synthesis of Carbohydrate-Containing Natural Compounds Cristina Nativi Department of Chemistry University of Florence - Italy Cristina Nativi Department of Chemistry University of Florence - Italy

The Biological Roles of Carbohydrates Glycosylation · PDF fileSYNAPS July 2011-The Biological Roles of Carbohydrates-Glycosylation Methods: O-, C-, N- Glycosylation; 2-deoxy Glycosides

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Page 1: The Biological Roles of Carbohydrates Glycosylation · PDF fileSYNAPS July 2011-The Biological Roles of Carbohydrates-Glycosylation Methods: O-, C-, N- Glycosylation; 2-deoxy Glycosides

SYNAPS July 2011

-The Biological Roles of Carbohydrates

- Glycosylation Methods: O-, C-, N- Glycosylation; 2-deoxy Glycosides

- Synthesis of Carbohydrate-Containing Natural Compounds

Cristina NativiDepartment of Chemistry

University of Florence - Italy

Cristina NativiDepartment of Chemistry

University of Florence - Italy

Page 2: The Biological Roles of Carbohydrates Glycosylation · PDF fileSYNAPS July 2011-The Biological Roles of Carbohydrates-Glycosylation Methods: O-, C-, N- Glycosylation; 2-deoxy Glycosides

SYNAPS July 2011

Carbohydrates prompt you thinking of …

Page 3: The Biological Roles of Carbohydrates Glycosylation · PDF fileSYNAPS July 2011-The Biological Roles of Carbohydrates-Glycosylation Methods: O-, C-, N- Glycosylation; 2-deoxy Glycosides

SYNAPS July 2011

O OHO OH

OHOH

HO

OH

OH

OH

OH

Furanoside Piranoside

Polyhydroxyl compounds(same reactivity)

Five-member vs six-member rings

Several stereocentres(many stereoisomers)

Two anomers (from open-chain to cyclic form)

Four Good Reasons to Dislike Carbohydrates

Carbohydrates include: oligo- and polysaccharides, alditols, aldonic-aldaric acids and deoxy-sugars

Page 4: The Biological Roles of Carbohydrates Glycosylation · PDF fileSYNAPS July 2011-The Biological Roles of Carbohydrates-Glycosylation Methods: O-, C-, N- Glycosylation; 2-deoxy Glycosides

SYNAPS July 2011

* The most abundant biological compounds on earth

* Are available in large quantities from natural sources

chemical industry has exploited their isolation, purificationmodification

* Constitute the structural element of all plants and the major constituents of shells of insects, crabs etc.

But Carbohydrates ....

Page 5: The Biological Roles of Carbohydrates Glycosylation · PDF fileSYNAPS July 2011-The Biological Roles of Carbohydrates-Glycosylation Methods: O-, C-, N- Glycosylation; 2-deoxy Glycosides

SYNAPS July 2011

Biological Roles of Carbohydrates

* Energy Source

* Starting Material in biosynthesis

* Biological Targets → Glycobiology

* Starting Material as “Chiral Pool” (Natural Compounds)

Page 6: The Biological Roles of Carbohydrates Glycosylation · PDF fileSYNAPS July 2011-The Biological Roles of Carbohydrates-Glycosylation Methods: O-, C-, N- Glycosylation; 2-deoxy Glycosides

SYNAPS July 2011

Biological Roles of CarbohydratesEnergy Source

Linkage 1-6

Linkage 1-6

o o o

o o o o o

Glycogen-phosphorylase

Debranchingenzyme

α 1-6glycosylase

Glycogen

Branched structure

Linear structure

Page 7: The Biological Roles of Carbohydrates Glycosylation · PDF fileSYNAPS July 2011-The Biological Roles of Carbohydrates-Glycosylation Methods: O-, C-, N- Glycosylation; 2-deoxy Glycosides

SYNAPS July 2011

Biological Roles of Carbohydrates

Energy SourceStarting MaterialGlucose Piruvate Acetyl CoAGlycogen Lactate + ATPGlucose-6-phosphate pentose phosphate + NADPH

O

OHHO

HOOH

OHO

OHHO

HOHOOPO3

2-

O

OHHO

HOOH

O P O P O

O O O OO

HO OH

N

HN

O

O

O

OHHO

HOOH

O OHO

OH

OH

OH

HO OHO

OH

OH

OH

ATP

ADP

Galacto-kinase

Galactose-1-phosphate

UTP

PPi

Uridinediphospho(UDP)-galactosylpyrophosphorylase

Uridinediphospho (UDP)galactoseUDP

Galactosyl-trasferase

Lactose

Page 8: The Biological Roles of Carbohydrates Glycosylation · PDF fileSYNAPS July 2011-The Biological Roles of Carbohydrates-Glycosylation Methods: O-, C-, N- Glycosylation; 2-deoxy Glycosides

SYNAPS July 2011

Biological Roles of Carbohydrates

Biological Target

Page 9: The Biological Roles of Carbohydrates Glycosylation · PDF fileSYNAPS July 2011-The Biological Roles of Carbohydrates-Glycosylation Methods: O-, C-, N- Glycosylation; 2-deoxy Glycosides

SYNAPS July 2011

Biological Roles of Carbohydrates

Page 10: The Biological Roles of Carbohydrates Glycosylation · PDF fileSYNAPS July 2011-The Biological Roles of Carbohydrates-Glycosylation Methods: O-, C-, N- Glycosylation; 2-deoxy Glycosides

SYNAPS July 2011

Biological Roles of Carbohydrates

Cell Adesion and Extracellular Matrix (ECM)

The ECM is a complex mixture of molecules with multiple functions:

1.Filling the space between cells, binding cells and tissue together2.Providing a lattice through cells can move3.Filtration4.Support and elasticity (see connective tissue)5.Influence on cell growth and differentiation (many cells interact with their ECM)

The ECM is composed of 3 types of macromolecules

1. Glycoproteins, glycoconjugates2. Glycosaminoglycans (GAGs): large unbrunched polymers of repeating disaccharides3. With the excetion of hyaluronic acid, all GAGs are covalently attached to core Proteins thereby forming a proteoglycan (PG)

Page 11: The Biological Roles of Carbohydrates Glycosylation · PDF fileSYNAPS July 2011-The Biological Roles of Carbohydrates-Glycosylation Methods: O-, C-, N- Glycosylation; 2-deoxy Glycosides

SYNAPS July 2011

Biological Roles of Carbohydrates

Type andnumber of

monosaccharidicunits are essential

to distinguish betweennormal or abnormal

cells

Page 12: The Biological Roles of Carbohydrates Glycosylation · PDF fileSYNAPS July 2011-The Biological Roles of Carbohydrates-Glycosylation Methods: O-, C-, N- Glycosylation; 2-deoxy Glycosides

Mucin Antigens

SYNAPS July 2011ACIE 2011, vol. 50 pag. 1770

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SYNAPS July 2011

Biological Roles of Carbohydrates

Type andnumber of the

monosaccharidicunits

Type of linkage

Page 14: The Biological Roles of Carbohydrates Glycosylation · PDF fileSYNAPS July 2011-The Biological Roles of Carbohydrates-Glycosylation Methods: O-, C-, N- Glycosylation; 2-deoxy Glycosides

Possible Mechanisms of Origin of TAAPossible Mechanisms of Origin of TAA1) New genetic information caused by a virus2) Alteration of ocogenes by carcinogenes, which can cause the induction of genes

normally unexpressed3) Uncovering of antigens normally hidden in the cell membrane4) Release, when neoplastic cells die, of antigens normally sequestered in the cell

TumorCell Tumor-Associated

Antigen (TAA, TSAs)

SYNAPS July 2011

Page 15: The Biological Roles of Carbohydrates Glycosylation · PDF fileSYNAPS July 2011-The Biological Roles of Carbohydrates-Glycosylation Methods: O-, C-, N- Glycosylation; 2-deoxy Glycosides

TumorCell

B cell/T cell

Tumour Antigen

During the growth of tumors,mechanisms that allow tumor-presentedantigens to be seen as “self”by their immune system havebeen identified (escape mechanisms)

TAA No molecolar recognitionis observed!

SYNAPS July 2011

TAA and ImmunotherapyTAA and Immunotherapy(Biologic Therapy)(Biologic Therapy)

Induce therapeutic cellular immunity in the tumor-bearing host

Page 16: The Biological Roles of Carbohydrates Glycosylation · PDF fileSYNAPS July 2011-The Biological Roles of Carbohydrates-Glycosylation Methods: O-, C-, N- Glycosylation; 2-deoxy Glycosides

Chromomycin A3Mithramycin,Olivomycin A

Biological Roles of Carbohydrates

Aureolic Acid Family Structurally related drugs synthesizedby different streptomycete species

2,6- dideoxy sugars

SYNAPS July 2011

Page 17: The Biological Roles of Carbohydrates Glycosylation · PDF fileSYNAPS July 2011-The Biological Roles of Carbohydrates-Glycosylation Methods: O-, C-, N- Glycosylation; 2-deoxy Glycosides

SYNAPS July 2011

Carbohydrates as Starting Material(Chiral Pool – Chirons)

Jean Baptiste Regnault

Achilles educated by ChironLouvre Museum

Chirons: Enantiomerically PureSynthons

Page 18: The Biological Roles of Carbohydrates Glycosylation · PDF fileSYNAPS July 2011-The Biological Roles of Carbohydrates-Glycosylation Methods: O-, C-, N- Glycosylation; 2-deoxy Glycosides

SYNAPS July 2011

OOH

HO

HOHO

OH

trans Vicinal

trans Vicinal

OOH

OHHO

HOOH

trans Vicinal

cis Vicinal

Types of Hydroxyl Groups Found in Sugars

OOH

HO

HOHO

OH

trans Vicinal

trans Vicinal

OOH

HO

HOHO

OH

Anomeric

Primary

Secondary

OOH

HO

HO

OH OH

trans Vicinal

cis Vicinal

Page 19: The Biological Roles of Carbohydrates Glycosylation · PDF fileSYNAPS July 2011-The Biological Roles of Carbohydrates-Glycosylation Methods: O-, C-, N- Glycosylation; 2-deoxy Glycosides

SYNAPS July 2011

Carbohydrates as Starting Material

Synthesis of (+)-Spectinomycin

S. Hanessian -Total Synthesis of Natural Product: The Chiron Approach

O

O O Me

HO OH

H

HO

OH

MeHN

MeHN

HO OO

O

OHOHNHMe

HO

MeHN

OHHO

Me

OO

OOH

NHMe

OH

MeHN

Me

OH

HOOH

O

OO

MeO

HO OH

OHMeHN NHMe

OHHO OH

OHMeHN NHMe O

OO

HO Me

+

Actinamine Spectinose

Aminocyclitol AntibioticStreptomices Spectabilis

Page 20: The Biological Roles of Carbohydrates Glycosylation · PDF fileSYNAPS July 2011-The Biological Roles of Carbohydrates-Glycosylation Methods: O-, C-, N- Glycosylation; 2-deoxy Glycosides

SYNAPS July 2011

OO

OOH

NHMe

OH

MeHN

Me

OH

HOOH

OO

OOH

NHMe

OH

MeHN

Me

OH OH

OHO

OOH

NHMe

OH

MeHN

Me

OH OH

OHHO OH

OHMeHN NHMeO

X

Me

OH OH+

OOH

HOHO

OH OH

D- Glucose Actinamine

Synthesis of (+)-Spectinomycin

Page 21: The Biological Roles of Carbohydrates Glycosylation · PDF fileSYNAPS July 2011-The Biological Roles of Carbohydrates-Glycosylation Methods: O-, C-, N- Glycosylation; 2-deoxy Glycosides

SYNAPS July 2011

OOH

HOHO

OH OH

D- Glucose

OOH

HOHO

HO OMe

MeOHHCl SO2Cl2

pyO

ClCl

HOHO OMen-Bu3SnHAIBN (rdn)

OHO

HO OMe

4,6-dideoxyderivative

OOO

HO OMe

SOO

Cl

Cl -

Nu -

α- anomer !

OOO

HO

OMeS

OO

Cl

Cl -

Nu -

β- anomer !

Synthesis of (+)-Spectinomycin

SN2 reaction

Page 22: The Biological Roles of Carbohydrates Glycosylation · PDF fileSYNAPS July 2011-The Biological Roles of Carbohydrates-Glycosylation Methods: O-, C-, N- Glycosylation; 2-deoxy Glycosides

SYNAPS July 2011

OHO

HO OMe

OHO

BzO OMe

O

HO HO OMe

O

AcOAcOCl

O

AcOAcOO

HO OH

CbzMeNOH

NMeCbz

O

AcO HO

O

TCCO OTCC

CbzMeNOTCC

NMeCbz

O

O O

O

TCCO OTCC

CbzMeNOTCC

NMeCbz

O

AcO O

O

TCCO OTCC

CbzMeNOTCC

NMeCbz

TCC = trichloroethoxycarbonylOMe

1) (Bu2Sn)2O MeOH reflux2) BzCl

1) PCC2) NaBH4

1) Ac2OBF3OEt2) HCl

Cbz-actinamineAgOTf, THF- 40 °C

MeONaMeOH

1) MeONa MeOH

2) MeC(OMe)3 TsOH, C6H6

3) ClCO2CH2CCl3 Py / DMAP

aq. Ac2O

Mild cond.

PCCbenzenereflux

Synthesis of (+)-Spectinomycin

Page 23: The Biological Roles of Carbohydrates Glycosylation · PDF fileSYNAPS July 2011-The Biological Roles of Carbohydrates-Glycosylation Methods: O-, C-, N- Glycosylation; 2-deoxy Glycosides

SYNAPS July 2011

Synthesis of (+)-Spectinomycin

O

AcO O

O

TCCO OTCC

CbzMeNOTCC

NMeCbz

O

HO OH

OO OH

CbzMeNOH

NMeCbz

O

O O

OO OH

CbzMeNOH

NMeCbz

SnBu Bu

O

O OH

OO OH

CbzMeNOH

NMeCbz

O

O O Me

HO OH

H

HO

OH

MeHN

MeHN

HO

Zn, MeOH (Bu2Sn)2O

MeOHreflux

1) NBS, benzene2) H2 - Pd/C, 2-PrOH

Page 24: The Biological Roles of Carbohydrates Glycosylation · PDF fileSYNAPS July 2011-The Biological Roles of Carbohydrates-Glycosylation Methods: O-, C-, N- Glycosylation; 2-deoxy Glycosides

SYNAPS July 2011

Types of Hydroxyl Groups Found in Sugars

OOH

HO

HOHO

OH

Anomeric

Primary

Secondary

Page 25: The Biological Roles of Carbohydrates Glycosylation · PDF fileSYNAPS July 2011-The Biological Roles of Carbohydrates-Glycosylation Methods: O-, C-, N- Glycosylation; 2-deoxy Glycosides

SYNAPS July 2011

Glycosylation Methods:Synthesis of O-Glycosides

Page 26: The Biological Roles of Carbohydrates Glycosylation · PDF fileSYNAPS July 2011-The Biological Roles of Carbohydrates-Glycosylation Methods: O-, C-, N- Glycosylation; 2-deoxy Glycosides

SYNAPS July 2011

OO

OX

+ HO

Glycosides and Glycosylation

ONH

OS

OCH2

Aglycon Donor Acceptor

O-glycoside

Page 27: The Biological Roles of Carbohydrates Glycosylation · PDF fileSYNAPS July 2011-The Biological Roles of Carbohydrates-Glycosylation Methods: O-, C-, N- Glycosylation; 2-deoxy Glycosides

SYNAPS July 2011

O-Glycosidic Bond Formation

O YRO

RO

OX

OR

+a)

X = LGY = O-

O O ORO

ORRO

b) Y = LGX = OH

ORO

RO

O

OR

O Lewis Acid = Promoter

Regiochemical problems

Page 28: The Biological Roles of Carbohydrates Glycosylation · PDF fileSYNAPS July 2011-The Biological Roles of Carbohydrates-Glycosylation Methods: O-, C-, N- Glycosylation; 2-deoxy Glycosides

SYNAPS July 2011

OO O

H

O

O

O

OLG

OH

R

α - face

O-Glycosidic Bond Formation

Path a)

O

LG

OH

Rβ - face

Path b)

Tricky equilibrium among donor, acceptor and promoter

Page 29: The Biological Roles of Carbohydrates Glycosylation · PDF fileSYNAPS July 2011-The Biological Roles of Carbohydrates-Glycosylation Methods: O-, C-, N- Glycosylation; 2-deoxy Glycosides

SYNAPS July 2011

OOR

HOHO

HO

OHO

OR

OH

HOHO

HO

O

OR

OHHO

HOHO

O OR

OHHOHO

Stereochemical Aspects of Glycoside Bond Formation

SN1 vs SN2

OOR

OH

HOHO

OH

OOR

OHHO

HOOH

O

OR

HOHO

HO

OH

O

OR

OHHOHO

1,2–trans -O-glycosides

1,2–cis -O-glycosides

Glc Gal Man Rha

Glc Gal Man Rha

Page 30: The Biological Roles of Carbohydrates Glycosylation · PDF fileSYNAPS July 2011-The Biological Roles of Carbohydrates-Glycosylation Methods: O-, C-, N- Glycosylation; 2-deoxy Glycosides

SYNAPS July 2011

Stereochemical Aspects of Glycoside Bond FormationNeighbouring Group Participation

OX

OR'

O

OR'

Promoter O

OR'

O

O O

R'

RO

H

RO

H

O

ORO

R'

OOR

OR'

1, 2 - cis glycoside

1, 2 - trans glycoside

Page 31: The Biological Roles of Carbohydrates Glycosylation · PDF fileSYNAPS July 2011-The Biological Roles of Carbohydrates-Glycosylation Methods: O-, C-, N- Glycosylation; 2-deoxy Glycosides

SYNAPS July 2011

Stereochemical Aspects of Glycoside Bond FormationSolvent Participation

O

R'

Et2O

MeCN

OO

R'

Et

Et

O

NR'

C

Me

RO

H

RO

H

O

R' OR

O

R'OR

Page 32: The Biological Roles of Carbohydrates Glycosylation · PDF fileSYNAPS July 2011-The Biological Roles of Carbohydrates-Glycosylation Methods: O-, C-, N- Glycosylation; 2-deoxy Glycosides

SYNAPS July 2011

OOH

HOHO

HOOH

H+ OOH2

HOHO

HOOH

OHO

HOHO

OH

MeOH O

OMe

HOHO

HOHO

OHO

HOHO

OH

+O

OMe

HOHO

HOHO

O

OMe

HOHO

HO

OH

α- Man

Fischer – Helferish Glycosylation

O

OMe

HOHO

HOHO

α- Glc

Page 33: The Biological Roles of Carbohydrates Glycosylation · PDF fileSYNAPS July 2011-The Biological Roles of Carbohydrates-Glycosylation Methods: O-, C-, N- Glycosylation; 2-deoxy Glycosides

SYNAPS July 2011

OOH

HOHO

HOOH

O

Br

RORO

RORO

Prom. ORO

RORO

OR

ORO

RORO

OR

ONu

RORO

ROOR

NuR = Ac, Bz, Piv Bn

Koenigs - Knorr Glycosylation

ORO

RORO

OR Br

ORO

RORO

OR Br

R

O H O NuRO

RORO

OR

ORO

RORO

OR

ONu

RORO

ROOR

ORO

RORO

OR Br

ORO

RORO

OR Br

R

O H O NuRO

RORO

OR

ORO

RORO

OR

ONu

RORO

ROOR

SN2 vs SN1Promoter

δ

δ δ

δ

Page 34: The Biological Roles of Carbohydrates Glycosylation · PDF fileSYNAPS July 2011-The Biological Roles of Carbohydrates-Glycosylation Methods: O-, C-, N- Glycosylation; 2-deoxy Glycosides

SYNAPS July 2011

Stereoselective Synthesis of Mannosyl cis-glycosides(β O-Man)

OOBn

Br

BnOBnO

BnOAg-silicate

OOBn

Br

BnOBnO

BnO

Ag

O

H

RO

OBn

ORBnO

BnOBnO

C-2 – non partecipant group (OBn)C-1 - SN2 reaction

Page 35: The Biological Roles of Carbohydrates Glycosylation · PDF fileSYNAPS July 2011-The Biological Roles of Carbohydrates-Glycosylation Methods: O-, C-, N- Glycosylation; 2-deoxy Glycosides

SYNAPS July 2011

Stereoselective Synthesis of Mannosyl cis-glycosides(β O-Man)

OOP

POPO

OYOH

OOBnO

OBnO

S(O)Ph

Ph

OPOPO

OYPO

OR

OPOPO

O

PO

OR

OPOPO

OPO

L

XOR

Post-glycosylation epimerizationwith O-nucleophiles Post-glycosylation stereoselctive

reduction of 2-ulosides

IAD (Intramolecular AglyconDelivery) followed by tether cleavage

Stereoselective mannosylationusing priviledged donors(benzylidene sulfoxides)

A B

C D

Page 36: The Biological Roles of Carbohydrates Glycosylation · PDF fileSYNAPS July 2011-The Biological Roles of Carbohydrates-Glycosylation Methods: O-, C-, N- Glycosylation; 2-deoxy Glycosides

SYNAPS July 2011

O

AcO Br

BnOBnO

BnOROH

Promoter

O

AcOOR

BnOBnO

BnODeacetylal. O

HOOR

BnOBnO

BnO

Inversionat C-2

OOH

ORBnO

BnOBnO

Stereoselective Synthesis of Mannosyl cis-glycosides

A

Page 37: The Biological Roles of Carbohydrates Glycosylation · PDF fileSYNAPS July 2011-The Biological Roles of Carbohydrates-Glycosylation Methods: O-, C-, N- Glycosylation; 2-deoxy Glycosides

SYNAPS July 2011

Stereoselective Synthesis of Mannosyl cis-glycosidesIAD (Intramolecular Aglycon Delivery)

OO

O

BnOBnO

BnO

LG

OO

O

BnOBnO

BnO

LG

OR O

O

OOH

BnOBnO

BnOO

R

O

R

H+

O-nucleophile

2-O-para methoxybenzyl mannoside

A variety of β O-mannosides can be obtained

DDQ

O

O+

Quinone-like species

Page 38: The Biological Roles of Carbohydrates Glycosylation · PDF fileSYNAPS July 2011-The Biological Roles of Carbohydrates-Glycosylation Methods: O-, C-, N- Glycosylation; 2-deoxy Glycosides

SYNAPS July 2011

Stereoselective Synthesis of Mannosyl cis-glycosidesSynthesis of β-O-Octyl-2-O-mannopiranosyl-α (1,2)-mannopyranoside

O

OO

OHHO

HO

HO

HOHO

HOO

OBnOBnO

BnOOH

OOBnO

BnO

BnO OAc

O NH

CCl3

OBnOBnO

BnOO O

OCH3

+

OrthoesterCommon intermediate

Dr. Gabriele Gabrielli Marco Palchetti

University of Florence

Page 39: The Biological Roles of Carbohydrates Glycosylation · PDF fileSYNAPS July 2011-The Biological Roles of Carbohydrates-Glycosylation Methods: O-, C-, N- Glycosylation; 2-deoxy Glycosides

SYNAPS July 2011

Stereoselective Synthesis of Mannosyl cis-glycosides

Synthesis of β-O-Octyl-2-O-mannopyranosyl-α (1,2)-mannopyranoside

OAcOAcO

AcO OAc

OAc

OAcOAcO

AcO

OAcOAcO

AcO O

Br

OO

OCH3BnBrNaH

DMF

2,6-Lutidine MeOH

HBr 33% inCH3COOH

CH2Cl2

K2CO3 cat.

MeOH

CHCl3

OHOHO

HO OH

OH

Ac2OPy

> 90%> 90%

73%

> 90%

OHOHO

HO OO

OCH3

85%

OBnOBnO

BnO OO

OCH3

O

β face!

Page 40: The Biological Roles of Carbohydrates Glycosylation · PDF fileSYNAPS July 2011-The Biological Roles of Carbohydrates-Glycosylation Methods: O-, C-, N- Glycosylation; 2-deoxy Glycosides

SYNAPS July 2011

Stereoselective Synthesis of Mannosyl cis-glycosidesSynthesis of β-O-Octyl-2-O-mannopyranosyl-α (1,2)-mannopyranoside

OBnOBnO

BnOOAc

ONH

Cl3C

O

OO

OAcBnO

BnO

BnO

BnOBnO

BnOO

OBnOBnO

BnO OAc

OH

Cl3CCN

DBUCH2Cl2

89%

OBnOBnO

BnO OO

OCH3

H+ / H2O99%

OBnOBnO

BnO OAc

ONH

Cl3C

+OBnO

BnO

BnO OHO

TMSOTf (cat)CH2Cl2

67%

Deprotect.

O

OO

OHHO

HO

HO

HOHO

HOO

Page 41: The Biological Roles of Carbohydrates Glycosylation · PDF fileSYNAPS July 2011-The Biological Roles of Carbohydrates-Glycosylation Methods: O-, C-, N- Glycosylation; 2-deoxy Glycosides

SYNAPS July 2011

How to Choose the Good Glycosyl Donor?

OOP

POPO

OYOH

OOBnO

OBnO

S(O)Ph

Ph

OPOPO

OYPO

OR

OPOPO

O

PO

OR

OPOPO

OPO

L

XOR

A B

C D

Page 42: The Biological Roles of Carbohydrates Glycosylation · PDF fileSYNAPS July 2011-The Biological Roles of Carbohydrates-Glycosylation Methods: O-, C-, N- Glycosylation; 2-deoxy Glycosides

SYNAPS July 2011

O

OPX O

OPSP O

OPOR O

OPXR

Glycosyl halides Thio derivatives O- Derivates Other derivatives

BromidesChlorides

FluoridesIodides

Sulfides(Thioglycosides)

SulfoxidesSulfones

ImidatesEsters

PhosphitesPhosphatesCarbonates

Selenoglycosides

Promoters for Glycosyl Bromides and Chlorides:

AgOTf, SnCl4, BF3 OEt2, AgClO4, TfOH, Ag2O, Ag silicate,

Types of Glycosyl Donors

Page 43: The Biological Roles of Carbohydrates Glycosylation · PDF fileSYNAPS July 2011-The Biological Roles of Carbohydrates-Glycosylation Methods: O-, C-, N- Glycosylation; 2-deoxy Glycosides

SYNAPS July 2011

Glycosyl Fluorides

• Too reactive to be activated under standard Koenigs-Knorr conditions• They were introduced late (1981)• More stable than chlorides and bromides• Can be activated under specific conditions consistent with several protecting groups• They are currently among the most frequently used donors

OOBn

BnOBnO

OBnOH O

OBn

BnOBnO

OBnF

DAST

THF-30 °C - rt

DAST = Diethylamino sulfur trifluoride

Promoters: SnCl2 + AgClO4 (Mukaiyama); SiF4 + TMSOTf (Noyori) BF3 OEt2 (Nicolaou, Kunz, Vozny) Cp2HfCl2 (metallocenes complexes) + AgClO4 or AgOTf (Suzuki)

99 % (α / β = 1 : 8)

Page 44: The Biological Roles of Carbohydrates Glycosylation · PDF fileSYNAPS July 2011-The Biological Roles of Carbohydrates-Glycosylation Methods: O-, C-, N- Glycosylation; 2-deoxy Glycosides

SYNAPS July 2011

Nicolaou’s Synthesis of Avermectin B1a

• Glycosyl fluorides have found use in the synthesis of a wide range of complex natural products.

• Avermectin B1 is the most effective in the family of Avermectin of natural productsagainst agriculturally important insects

O

O

MeOHO

MeO

MeO

MeO

Me

Me

OH OH

Me

OH

O

OO

O

Me

Me

MeH

Avermectin B1a

αα--LL--oleandrosyloleandrosyl--αα--LL--oleandrosyloleandrosyldisaccharidedisaccharide

Milbemycin

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SYNAPS July 2011

Nicolaou’s Synthesis of Avermectin B1a

O

SPh

MeOTBSO

Me DAST-NBS80%

O

F

MeOTBSO

MeO

SPh

MeOHO

Me

SnCl2 AgClO4Et2O, 65%

O

O

MeOTBSO

Me

O

SPh

MeO

Me

DAST-NBS85%

O

O

MeOTBSO

Me

O

F

MeO

MeSnCl2 AgClO4Et2O, 65%

O

O

MeOTBSO

MeO

MeO

MeO

Me

Me

OH OTBS

Me

OH

O

OO

O

Me

Me

Me

O

O

MeOHO

MeO

MeO

MeO

Me

Me

OH OH

Me

OH

O

OO

O

Me

Me

Me

H

H

Avermectin B1a

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SYNAPS July 2011

Glycosyl Iodides

• Instable• Glycosylation proceed through in situ generation of glycosyl iodide intermediates by activating glycosyl bromide with tetralkylamonium iodide

O

I

MeO2CPivO

PivOPivO

+ O

PivO

NMeH

HHO

I2CH2Cl2

55%

OMeO2C

PivOPivO

PivO

O

PivO

NMeHH

O

3-O-Pivaloyl morphine

OHO2C

HOHO

HO

O

HO

NMeHH

O

Morphine-6-gluconoride

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SYNAPS July 2011

Synthesis of Glycosides from Anomeric Thio Derivatives

• Readily prepared by nucleophilic substitution at the anomeric center• Remarkably stable• They tolerate diverse protecting group manipulations• They are inert under several glycosylation conditions (useful acceptors)• Despite their stability they can be activated with thiophilic reagents

(soft electrophilic reagents under mild conditions)

OX + RSH

OSR

X = OAc (1,2-trans), Cl, Br

Lewis Acid

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SYNAPS July 2011

OSR' Electrophile O

S R'E

-R'SE O ROHO

OR

sulfonium ion

Promoter

Me SMe

S MeTfO-

DMTST dimethyl(methylthio)solfonium triflate

Me SMe

S Me

BF4-

DMTSF

SS

O OMe

MBPTS-(4-methoxyphenyl)benezenethiosulfinate

SN I

O

OO

NISacN-Iodosaccharine

Synthesis of Glycosides from Anomeric Thio Derivatives

R' (Aglycon)

N

N

O

N

S

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SYNAPS July 2011

Synthesis of Glycosides from Anomeric Thio Derivatives

An unique feature of thioglycosides is that their reactivity can be turned not only by the protecting groups of the sugars but also by the choice of the aglycone.

OS

OAc

AcOAcO

OBn O

N+

OBzO OH

BzOBzO

SEt

OBzO O

BzOBzO

SEt

OOAc

AcOAcO

BnOAgOTfCH2Cl2

98%α only

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SYNAPS July 2011

OOAc

AcOAcO

OAcOH O

OAc

AcOAcO

OAcO

NH

CCl3CCl3CN, K2CO3

CH2Cl2, RT54%

Glycosyl Trichloroacetimidates

• Glycosyl acetimidates were introduced by Sinaÿ(synthesis of the blood group B determinant)

• Glycosyl trichloroacetimidates were developed by Schmidt

OOBn

BnOBnO

BnOOH CCl3CN, NaH

CH2Cl2, RT96%

OOBn

BnOBnO

BnO O CCl3NH

• Relatively stable under neutral o basic conditions but extremely reactive under acidic conditions• Can be purified by column chromathography on silica gel

α

β

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SYNAPS July 2011

50

%

Min20 40

NaH

α

β

OOBn

BnOBnO

BnOOH

OOBn

BnOBnO

BnO O CCl3NH

OOBn

BnOBnO

BnOO CCl3

NH

BaseCl3C CN

50

20 40

α

β

% K2CO3

h

The electron-deficient nitrile readly adds to the free hydroxyl group; under week-basic conditions the kinetic product is formed (b), with strong base the thermodinamic product is obtained (a).

Glycosyl Trichloroacetimidates

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SYNAPS July 2011

OOBn

BnOBnO

BnOO CCl3

NH

O

OMe

HOBnO

BnOBnO

+TMSOTf

Et2ORT, 1h

OOBn

BnOBnO

BnOO

O

OMe

BnOBnO

BnO83%

α / β = 8:1

+O

OMe

HOBnO

BnOBnO

BF3Et2OCH2Cl2

- 20 °C2h

OOBn

BnOBnO

BnOO

O

OMe

BnOBnO

BnO90%

α / β > 1:19

OOBn

BnOBnO

BnO O CCl3NH

+ Cl3C

O

NH2

Glycosyl Trichloroacetimidates

Cl3C

O

NH2 - H2OCl3C CN

• Several promoter can be successfully used• Molecular sieves

Catalytic process?

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SYNAPS July 2011

Glycosyl Trichloroacetimidates

The normal and inverse procedureThe normal and inverse procedure

O

O

Me

BnO OBnOBn

NH

CCl3O O

OHOAcO

AcOAcO

OAcOBn

N3

OTBS+ O OOO

AcO

AcOAcO

OAcOBn

N3

OTBS

OMe OBnOBnBnO

TMSOTfEt2O

RT

Normal procedure: 43%Inverse procedure: 78%

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SYNAPS July 2011

Glycosyl Trifluoroacetimidates

• Recently introduced as glycosyl donor• The conversion of trifluoroacetimidates into glycosides are

promoted by the same reagents used for trichloroacetimidates

OOH + N

Cl CF3

PhK2CO3

CH2Cl2, RT

OO

N

CF3

Ph

OO

N

CF3

PhO

ORTMSOTf

CH2Cl2, RT

N-substituted trifluoroacetimidoyl chloride

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SYNAPS July 2011

Synthesis of Dioscin(spirostan saponin)

OOBz

BzOBzO

BzOO CF3

NH+

O

O

Me

HO

MeMe

Me

Diosgeninbenzoylated trifluroacetimidate

TMSOTf

CH2Cl2, RT92%

O

O

Me

O

MeMe

Me

OOBz

BzOBzO

BzOa. NaOMeb. PivCl, Py 60%

O

O

Me

O

MeMe

Me

OOPiv

HOPivO

HO

O

O

Me

O

MeMe

Me

OOPiv

OPivO

O

O O

OAc

MeAcO

AcO

NHCCl3

TMSOTf66%

O

Me

AcO

AcO

AcO

OMeAcO

AcO OAc

NaOMe MeOH-H20-THF

90%O

O

Me

O

MeMe

Me

OOH

OHO

O

O

Me

HO

HO

HO

OMeHO

HO OHDioscin

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SYNAPS July 2011

ORO

RORO

DMDO

99%α / β = 20:1

ORO

RORO

O+

O

R = AcR = BnR = TBDMS

α + β mixturehigh yield; α / β = 20 / 1high yield; only α

OO

DMDO

1,2-Anhydro Derivatives

• 1,2-Anhydro sugars such as Brigl’s anhydride has been known for a long time• Lemieux used 1,2-anhydro sugars in the first synthesis of sucrose (1953)• Curci (1980) and Murray (1985) developed the DMDO reagent• Danishefsky developed an efficient synthesis of anhydro sugars with DMDO• Seeberger employed anhydro sugars as donors in automatic oligosaccaride synthesis

O

OTBDMSTBDMSO

TBDMSO

OOO

TBDMSO

O

OTBDMSTBDMSO

TBDMSOO

Ph OOO

TBDMSO

Ph O

OOO

TBDMSO

Ph

O

OO

TBDMSO

Ph

OGulo

Allo

Gal

Brigl’s anhydride

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SYNAPS July 2011

OBnO

BnOBnO

DMDO99%

α:β / 20:1

OBnO

BnOBnO

O

OHO

BnOBnO

ZnCl2THF, - 78 °C- rt

56%

OBnO

BnOBnO

ROO

OBnOBnO

R = HR = Bn

DMDO

OBnO

BnOBnO

ROO

OBnOBnO

O

OHO

BnOBnO

ZnCl2THF, - 78 °C- rt32% for 2 steps

OBnO

BnOBnO

ROO

OBnOBnO

RO OO

BnOBnO

1,2-Anhydro Derivatives

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SYNAPS July 2011

Solid-Phase Synthesis Using Glycal-Derived1,2-Anhydrosugars

O

OSiPh2O

O

ODMDO O

OSiPh2O

O

O

O

O

OHO

O

OO

OSiPh2O

O

O

HOO

O

O

O

DMDO

O

OSiPh2O

O

O

HOO

O

O

O

O

OO

O

OHO

O

O

OSiPh2O

O

O

HOO

O

O

OO

O

O

OHO

O

O

DMDO

O

OSiPh2O

O

O

HOO

O

O

O

O

OO

O

OHO

O

O

OHO

O

OO

OHO

OHO

OO

O

O

O

OO

O

OHO

O

OO

O

OHO

TFA, AcOH32 %

overall yield

O

O O

O

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SYNAPS July 2011

N-Pentenyl Glycosides

• Introduced by Fraser-Reid• Highly stable glycosyl donors• Activate by halogenation of the double bond• A major difference in the reactivity of n-pentenyl glycosides possessing

benzyl protecting groups compared to acylated glycosides was observed

O

X

OHO

X

Oacid

X = OH, OAc, Br, OCOR

HO

acid = H+, SnCl4 , AgOTf, NIS(depending on X and protecting groups)

Masked Glycosyl Donor

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SYNAPS July 2011

N-Pentenyl Glycosides

Glycosylation with n-pentenyl glycosides

N

O

O

IEt3SiOTf

N

O

O

I

SiEt3

N

O

O

SiEt3

I++

O

X

O I+ O

X

O

IO

X

O

I

O

I

-

O

X

ROH O

X

OR

OTf

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SYNAPS July 2011

OOBn

BnOBnO

OBnOPent + O

OH

BzOBzO

BzO OPent

IDCP = iodonium dichollidine perchlorate (moderate promoter)NIS-TfOH (powerful promoter)

IDCP

CH2Cl2 -Et2O63%

OOBn

BnOBnO

BnO O OBzOBzO

BzO OPent

O

HN

O

CO2Bn

NHCO2Bn

HO

BnOBnO

BnO

NIS-TfOHCH2Cl2

42%

OOBn

BnOBnO

BnO O OBzOBzO

BzOO

O

HN

O

CO2Bn

NHCO2Bn

BnOBnO

BnO

N-Pentenyl Glycosides

Armed – Disarmed Concept

Armed Disarmed

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SYNAPS July 2011

Glycosylation Methods:Synthesis of 2-Deoxy-O-Glycosides

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SYNAPS July 2011

Special Problems in Glycosylation Reactions:2-Deoxy Sugars

O OHOHO OH

HO

HOHO OH

2-deoxy glucose 2-6-dideoxy glucose

2 2

6

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Chromomycin A3

Deoxy Carbohydrates

Aureolic Acid Family Structurally related drugs synthesizedby different streptomycete species

2,6- dideoxy sugars

SYNAPS July 2011

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SYNAPS July 2011

Special Problems in Glycosylation Reactions:2-Deoxy Sugars

O OHOHO OH

HO

HOHO OH

2-deoxy glucose 2-6-dideoxy glucose

2 2

6

• 2-Deoxy and 2,6-dideoxy glycosides are important structural units in many naturalproducts including antitumor drugs, antibiotics active against Gram-positive bacteria, cardiac glycosides, antiparasitic agents• The lack of a stereodirecting neighbouring group adjacent to the anomeric centermakes 2-deoxyglycoside synthesis a real challenge• The absence of electron-withdrawing substituent at C-2 makes the glycosidic bondMuch more acid-labile giving rise to easy hydrolysis or anomerization

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SYNAPS July 2011

Special Problems in Glycosylation Reactions:2-Deoxy Sugars

ORO

RORO

ORO

RORO

Y

YX

ORO

RORO

X

Y

X

ORO

RORO

YX

ORO

RORO X

Yα-Manno β-Gluco

S S

ORO

RORO

Y

SX

ORO

RORO

XY

ORO

RORO

Y

SX

ORO

RORO

Y Xβ-Manno α-Gluco

Y = participating group, easily removable

Temporary Assistance

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SYNAPS July 2011

Special Problems in Glycosylation Reactions:2-Deoxy Sugars

Addition of PhSCl to glycals was introduced by Schmidtand widely investigate by Roush

Addition of Sulfur-based Electrofiles to Glycals

O

X

ROTBDSO

O

X

RO

TBDSO

4H55H4

O

X

ROTBDSO

SPhO

XRO

TBDSOCl

SPh O

X

ROTBDSO

SPh

O

X

RO

TBDSO

SPh

OX

ROTBDSO

ClPhS

X = Br, Cl, OTs 5H4 is favouredProtecting group at C-4 influences the

up-, bottom-face attack (TBDS favoures the bottom-face attack)

Episulfoniumspecies

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SYNAPS July 2011

Special Problems in Glycosylation Reactions:2-Deoxy Sugars

OX

AcOTBDSO

ClPhS

OX

AcOTBDSO

OPhS NH

CCl3

OX

AcOTBDSO OR

PhS

OX

AcOTBDSO

SPhO

X

OAc

TBDSO

PhS

OX

AcOTBDSO OR

PhS

OX

AcOTBDSO

ORPhSO

X

AcO

TBDSO

SPh

1) DBU, THF-H2O2) NaH, CCl3CN- 40 °C - - 20 °C

TMSOTf, ROHCH2Cl2 , - 78 °C

SN2 DisplacementTMSOTf, ROHCH2Cl2 , - 78 °C

ROH Felkin-Anh ControlO

X

AcOTBDSO

SPh

ROH

ROHROH

Stereoelectronic Control

SN2 Displ.

20-50% in glycosylationof hindered alcohols

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SYNAPS July 2011

Special Problems in Glycosylation Reactions:2-Deoxy Sugars

Removal of Temporary Protecting Group

OX

AcOTBDSO OR

PhS

Raney- Nichel OX

AcOTBDSO OR

H

H

2-Deoxy-β-O-glycoside

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SYNAPS July 2011

Special Problems in Glycosylation Reactions:2-Deoxy Sugars

Addition of Selenium-based Electrofiles to Glycals

OBnOBnO

BnO OAcPhSe

OBnOBnO

BnO

PhSeClAgOAc

toluene25 °C, 1h

+O

HOBnO

BnOOMeBnO

α / β = 1 / 981%

TMSOTfEt2O, 0 °C15 min

OBnOBnO

BnO OPhSe OBnO

BnOBnO OMe

α / β = 1 / 1698%

OBnOBnO

BnO OOBnO

BnOBnO OMe

Ph3SnHAIBN

H

H

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SYNAPS July 2011

Special Problems in Glycosylation Reactions:2-Deoxy Sugars

OBnO

BnOBnO

O+ O

OBnBnO

HO ZnCl2

42%

OBnO

BnOBnO

OHO

O

OBnBnO

OBnO

BnOBnO

O

OO

OBnBnO

SO

F F

F

FF

OBnO

BnOBnO O

O

OBnBnOBu3SnH

AIBN90%

77%S

O

F F

F

FF

Cl

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SYNAPS July 2011

The Cycloaddition Approach to 2-Deoxy-O-GlycosidesA new reagent ….

N

O

O

SCl

NK

O

O

N

O

ON

O

O

SSCH2Cl2, r.t.

= PhthNSClN

O

ON

O

O

SS

SO2Cl2

40 °C, 36h

> 90%

> 90%

S2Cl2

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SYNAPS July 2011

The Cycloaddition Approach to 2-Deoxy-O-GlycosidesA new reagent ….

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SYNAPS July 2011

The Cycloaddition Approach to 2-Deoxy-O-GlycosidesA new reagent …..

Y

O O

SNPhth

H

Y

O O

SY

O - O

S NPhth

Y = R, OR, SR,

- PhthN -

Y

O O

SNPhth

HY

O O

Y

O OSiMe3

PhthN-SCl

CHCl3, rt

Base

N

O

O

SCl = PhtN-SCl

Unstable

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SYNAPS July 2011

The Cycloaddition Approach to 2-Deoxy-O-GlycosidesA new reagent …..

O O

SNPhth

H

- PhthN -

BaseO

S

O O

O

S

O

O

O

LUMO (eV)

HOMO (eV)

0.19

5.58

- 9.80- 9.01

[4+2]S

O

O

Ab initio 3-21G*

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SYNAPS July 2011

The Cycloaddition Approach to 2-Deoxy-O-GlycosidesA new reagent …..

EDG EDG

OH

EDG

O

SSNPhth EDG

O-

SNPhth

OH

EDG = R, OR, OH, Cond. Ar. Ring

PhthN-SCl - PhthN -Base

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SYNAPS July 2011

The Cycloaddition Approach to 2-Deoxy-O-GlycosidesA new reagent …..

OH O

SSNPhth

O

SO

O

S

O O

LUMO (eV)

HOMO (eV)

- 0.26

5.58

- 8.98- 9.01

Base

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SYNAPS July 2011

The Cycloaddition Approach to 2-Deoxy-O-Glycosides

O O

SNPhth

H

- PhthN -

Base

O

S

O O

O[4+2]S

O

O

Cycloaddition on Solid Support

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SYNAPS July 2011

The Cycloaddition Approach to 2-Deoxy-O-Glycosides

+ OBnO

BnOBnO

CHCl3r.t.

OBnO

BnOBnO

S OO

OBnO

BnOBnO

SO

O

95 : 5

O O

S

α-O-glicoside β-O-glicoside

+

OBnO

BnOBnO

SO

O

α-O-glicoside

OBnO

BnOBnO

OS

O

β-O-glicoside

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SYNAPS July 2011

The Cycloaddition Approach to 2-Deoxy-O-Glycosides

SO

+ OBnO

BnOBnO

CHCl360 °C

OBnO

BnOBnO

S O OBnO

BnOBnO

SO

80 : 20β-O-glycosideα-O-glycoside

+

SOOH

PhthNSCl PyOH

SNPhth

CHCl3

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SYNAPS July 2011

The Cycloaddition Approach to 2-Deoxy-O-Glycosides

OBnO

BnOBnO

OO

OHO

OOBnBnO

BnO

OBnO

BnO

BnO

OAcO

AcOAcO

OBnO

BnOBnO

S OO

OO

OHO

S OO

OOBnBnO

BnO

S OO

OBnO

BnO

BnO

SO

O

Dienophile Cycloadduct Yield % ΔE (HOMO-LUMO)eV

80

54

73

68

7.91

7.91

7.55

7.88

8.12No Reaction

α /β

95/5

only α

only α

only β

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SYNAPS July 2011

The Cycloaddition Approach to 2-Deoxy-O-Glycosides

OBnOBnO

BnO

OHOHO

t BDMSO

OBnOBnO

t BDMSO

OBnO

BnO

OBn

O

BnO

BnO

O

BnO OBn

OBnOBnO

BnO

S O

OHOHO

t BDMSO

S O

OBnOBnO

t BDMSO

S O

OBnO

BnO

OBn

S O

O S

O

Dienophile Cycloadduct Yield (%)

80/20

95/5

92/8

only α

only β

α / β

85

69

80

68

73

BnO OBn

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SYNAPS July 2011

The Cycloaddition Approach to 2-Deoxy-O-Glycosides

OBnO

BnOBnO

S O

OBnO

BnOBnO

OTHF

OBnO

BnOBnO

S O

O

O

OBnO

BnOBnO

OO

O

THF

OOBnBnO

BnOS O

O

O

OOBnBnO

BnOO

OO

THF

O

O

S

BnOOBnO

O

BnOOBnTHF

Raney-Ni

68%

Raney-Ni0-25 °C

45%

Raney-Ni0-25 °C

31%

Raney-Ni

60°C

57%

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SYNAPS July 2011

The Cycloaddition Approach to 2-Deoxy-O-Glycosides

OH

COOMe

CbzHN

OH

COOMe

CbzHN

SNPhth

OBnO

BnOBnO

OH

COOMe

CbzHN

SNPhth OBnO

BnOBnO

S O

CbzHN COOMe

OBnO

BnOBnO

O

COOMeCbzHN

+ py60%

PhthNSCl60%

Raney-Ni

58%(82%)

(89%)

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SYNAPS July 2011

ROOBn

O O NHBoc

ORO

OBnO O NHBoc

OSNPhth

PhthNSClRO

OBnO O NHBoc

OS

OOBn

BnOBnO

Base

O

S OO

RO

OBn

BnOBnO

NHBoc

OOBn

R = Me, tBu, Ph, Me3SiCH2CH2

HOOBn

O NHBoc

O

50-60%

The Cycloaddition Approach to 2-Deoxy-O-Glycosides

Chiara VenturiUniversity of Florence

2−Deoxy−α-O-Glucoaminoacid

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SYNAPS July 2011

OOR

RORO RO

OR'O O NHR''

OS

OOR

RORO

S OO

RONHR''

OOR'

+

The Cycloaddition Approach to 2-Deoxy-O-Glycosides

Glycopeptide Mimetics with Native Sugar Peptide Linkage

αα--OO--glycosylglycosylhomoglutamatehomoglutamate

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SYNAPS July 2011

X

Z YC

B

X

Z YB

AX

Z YC

A

X

Z YC

A

B

a

bc

X, Y, Z = functional groupsA, B, C = orthogonal protecting groupsa, b, c = orthogonal deprotection cond.

Orthogonal protecting groups are “a set of completely independent classes of protecting groupssuch that each class can be removed in any order and in the presence of all other classes”Baranay & Marrifield

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SYNAPS July 2011

The Cycloaddition Approach to 2-Deoxy-O-Glycosides

O

S OO

Me3SiCH2CH2O

OBn

BnOBnO

NHBoc

OOBn

O

S OO

HO

OBn

BnOBnO

NHBoc

OOBn

TBAFTHFr.t.80%

O

S OO

NH

OBn

BnOBnO

NHBoc

OOBn

OtBu

OtBuO

HOBT, EDCI, DIPEADMF, rt, 86% tBuO

O

OtBu

H2N

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SYNAPS July 2011

The Cycloaddition Approach to 2-Deoxy-O-Glycosides

O

S OO

MeO

OBn

BnOBnO

NHBoc

OOBn

O

S OO

MeO

OBn

BnOBnO

NH2

OOBn

Me3SiCl (4M)PhOH (4M)CH2Cl2

O

S OO

MeO

OBn

BnOBnO

NH

OOBn

N-Cbz-L-Phe ONHCbz

O

S OO

MeO

OBn

BnOBnO

NH

OOBn

N-Fmoc-(N-Boc)-TrpO

NHFmoc

NBoc

66% (2 steps)

62% (2 steps)

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SYNAPS July 2011

The Cycloaddition Approach to 2-Deoxy-O-Glycosides

O

S OO

MeO

OAc

BnOBnO

NHAc

OOBn

O

S OO

MeO

OH

BnOBnO

NHAc

OOBn

Ac2OMe3SiOTf MeONa

rt86%- 40 °C

68%

O

S OO

MeO

OBn

BnOBnO

NHBoc

OOBn

O

S OO

MeO

O

BnOBnO

NHAc

OOBn

O

AcO

SPh

OAc

AcOAcO

NISTfOH

CH2Cl20 °C-rt

O

AcO

OAc

AcOAcO

64%β / α = 5/1

MeOH-CH2Cl2

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SYNAPS July 2011

The Cycloaddition Approach to 2-Deoxy-O-Glycosides

O

S O

ROH O

SOH

OR O OR

β-attack

L. A.

Raney-Ni

O

S O

O

O

Raney-Ni

α-O-glycoside

β-O-glycoside

α-O-glycoside

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SYNAPS July 2011

OBnO

BnOBnO S

OO

OHTMSOTf

CH3NO2

OBnO

BnOBnO S

O

OOH

+

α / β = 9/1 (74%)

23 h

The Cycloaddition Approach to 2-Deoxy-O-Glycosides

OBnO

BnOBnO S

O

OOH

OHTMSOTf

CH3NO2

OBnO

BnOBnO S

O

OOH

OBnO

BnOBnO S

OO

+ +

7%

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SYNAPS July 2011

The Cycloaddition Approach to 2-Deoxy-O-Glycosides

OBnO

BnOBnO S

OO

OBnO

BnOBnO S

OAcO

1) LiAlH42) Ac2O

OBnO

BnOBnO S

OO

OBnO

BnOBnO S

OTiCl4

O

Zn

Nysted

OBnO

BnOBnO S

OH

ORROHMeOTfMeNO2

OBnO

BnOBnO S

O

ORROHTfOHCH2Cl2

Nysted Reagent

60-70%

98%

ZnBrBrZn

Promoter

β- attach

The Remote Activation Concept

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SYNAPS July 2011

The Cycloaddition Approach to 2-Deoxy-O-Glycosides

OBnO

BnOBnO S

OH

O

OBnO

BnOBnO S

OH

O

OBnO

BnOBnO S

OH

O

OBnO

BnOBnO S

OH

O

OH

OBnO

BnOBnO S

OH

O

OOO

OO

OH

OOMeBnO

BnOBnO

OOMeBnO

BnOBnO

HO

OBnO

BnOBnO S

OAcO

O-Glycoside Donor AcceptorReaction Time (min.) Yield (%)

r.t.

2 equiv.

3 equiv.α / β = 5/95

2 equiv.

2 equiv.

5r.t. 61

40r.t. 68

40

45

35

50

r.t.

r.t.

HO5225

HOO

OO

OO

2-Deoxy-β-O-glycosides

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SYNAPS July 2011

The Cycloaddition Approach to 2-Deoxy-O-Glycosides

OBnO

BnOBnO S

OH

O

OBnO

BnOBnO S

OH

O

OBnO

BnOBnO S

OH

O

OBnO

BnOBnO S

OH

O

OOMeBnO

BnOBnO

OBnO

BnOBnO O

OBnO

BnOBnO O

OBnO

BnOBnO O

OOMeBnO

BnOBnO

Raney-Ni

Raney-Ni

Raney-Ni

Raney-Ni

OBnO

BnOBnO O

67%

69%

51%

56%

O

OO

O OO

OO

O O

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SYNAPS July 2011

Glycosylation Methods:Synthesis of C-Glycosides

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SYNAPS July 2011

Naturally Occurring C-GlycosidesAloin is an irritant laxative contained in the yellow sap of Aloe,which is a constituent of the

Anthraquinone complex.

Anthraquinone naturally occurs in some plants (eg. aloe, senna, rhubarb), fungi, lichens, and insects,where it serves as a basic

skeleton for their pigments. Natural anthraquinone derivatives tend to have laxative effects.

3-Beta-D-ribofuranosylmaleimideantineoplastic antibiotic isolated

from streptomyces showdoensis

O

HO

HOH

OH

OH OHOH

HO

Aloin

O

HO

HOO

HO

O

O HO

(OH)nAnthraquinones

OHO NH

HO OH

O

O OHO

NNH

HO OH

NN NH2

Showdomycin Formycin

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SYNAPS July 2011

O OR

n HO

O C

n HOO OR

n HO

O C

n HO

O-glycosides C-glycosides

C-Glycosides

Bond lenghtVan der Waals radiusElectronegativityDipole momentH-BondingAnomeric effectExoanomeric effectStability

O-C = 1.43 AO = 1.52 AO = 3.51C-O = 0.74 DTwoYesYesCleaved by acids and enzymes

O-C = 1.54 AO = 2.0 AC = 2.35C-C = 0.3 DNoneNoNoStable to acids and enzymes

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SYNAPS July 2011

OOAc

AcOAcO

OAcOAc O

OAc

AcOAcO

AcO

OOAcAcO

AcOOAc

OAcO

OAcAcO

AcOAcO

OAcO

AcOAcO

OAcOAc

OAcO

AcOAcO

OAc

OOAc

OAcO

OAcOAc

OAcO OAc

AcOOAc

OOAc

OAcO

AcOO

AcO OAc

AcOOAc

SiMe3

CH3CN, 4 °C, 48 hCH2Cl2, 50 °C, 6h

BF3OEt2 5 equiv.

3 equiv.

72 % α:β = 1:181 % α:β = 95:5

CH2Cl2, 50 °C, 6h

CH3CN, 4 °C, 48 h

78 % α:β = 1:180 % α:β = 95:5

CH3CN, 4 °C, 48 h 68 % α:β = 4:1

CH3CN, 4 °C, 48 h 55 % α:β = 99:1

OOBn

BnOBnO

OBnOAc

OOBn

BnOBnO

OBnX

C-Glycosylation with Allylsilanes

OOR

RORO

NHAcR'

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SYNAPS July 2011

O

BnO OBnOBn

L- Fuc

N+ O

Boc

N N

RuCl

Cl

PCy3Ph

MesMes

O

BnO OBnOBn

NO

Boc

Grubbs = 1,3-dimesityl-4,5-dihydroimidazol- 2-ylideneruthenium carbene

O

HO OHOH

NHCO2H

Boc

1. CrO3, H+

2. H2 / C, cat.

C-Glycosylation with Allylsilanes

Martina CacciariniUniversity of Florence

Alberto MarraUniversity of Ferrara

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SYNAPS July 2011

Metathesis Reactions

Metathesis is a bimolecular process involving the exchange of bondsbetween the two reacting chemical species, which results in the creation of products with similar or identical bonding affiliations

An important and influential reaction within organic chemistry, which involves the principle of metathesis is the olefin metathesis reaction developed by Yves Chauvin, Richard R. Schrock and Robert H. Grubbs, who shared a Nobel Prize in Chemistry in 2005.

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SYNAPS July 2011

Cy = N-heterocyclic carbene

PCy3

RuCl

Cl

PCy3Ph

Grubbs 1st generation catalyst

Mesitylen =

PCy3

RuCl

Cl

N N

RuCl

Cl

MesMes

Oi-Pr

Oi-Pr

Hoveyda-Grubbs 1st generation catalyst Hoveyda-Grubbs 2nd generation catalyst

Metathesis Catalyst Technology

Dissociation rate 170 times greater!

Similar reactivity as Grubbs 1st gen.useful in the industrial productionof macrocycles via RCM

Initiates readely at low temperature,efficient for the methatesis ofelectron-deficient or sterically demandind substrates

N N

RuCl

Cl

PCy3Ph

MesMes

Grubbs 2nd generation catalyst

N N

RuCl

Cl

PPh3Ph

MesMes

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SYNAPS July 2011

Metathesis Catalyst Technology

N N

RuCl

Cl

PCy3Ph

MesMes - PCy3

+ PCy3

N N

RuCl

ClPh

MesMesR R

RR

[Ru]Ph

[Ru]

R R

Ph

R

Ph[Ru]

R

Ph

R

Different initiation ratevarying the detachable

phosphine ligands

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SYNAPS July 2011

OOH

ROHO

HOOH

(CH2)nCH3

O

(CH2)nCH3

O

NaHCO3+

OOH

ROHO

HO O

(CH2)nCH3

Solvent: H2O + cosolvent (THF, CH3CN, EtOH)

R = HR = α-D-Glc n = 0, 5, 8

β-Glycosidic Ketones in Aqueous Media

Marie-Christine ScherrmannUniversite’ de Paris XI

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SYNAPS July 2011

OOH

HOHO

NHAcOH

O

O+

OOR

RORO

NHAc

ORO

RORO

NHAc

O O

R = H

R = Ac

Ac2OPy

100%

Ac2OPy

100%

R = H

R = Ac

NaHCO3

H2OTHF83%

+

4 : 6

OO

O

HOHO

HONHAc

NaO

O

O

HOHO

HO

NHAcNa

OO

O

HOHO

HO

NHAcNa

β-Glycosidic Ketones in Aqueous Media

OOHHO

HOR

OH

R = OH; GalR = NHAc; GalNAc

O

O+

NaHCO3 OOHHO

HOR

O

Ac2OPy O

OAcAcO

AcOR

OR = OAc; 100%R = NHAc; 50% (2 steps)

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SYNAPS July 2011

Glycosylation Methods:Synthesis of N-Glycosides

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SYNAPS July 2011

O

OH

HN

OO

NH

Asparagine

N-Glycosides

N-Glycosides Natural Glycoproteins (Saccaride units covalently linked to a peptide backbone)

The structural and biological diversity emerging from the combination of the aminoacid

and carbohydrates is immense

N-Acetylgalactosamine

N-Acetylglucosamine

D-Glucose

L-Rhamnose

β-N-glycoside

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SYNAPS July 2011

N-Glycosides

OOH

[P]OO

NH2

[P]ONH4HCO3

H2O

OOAc

[P]OTMSN3

SnCl486%

ON3

[P]OPR3

H2O - THFO

NH2

[P]O

PR3

ON

[P]ON N PR3

phosphazide

- N2 ON

[P]O

PR3

OO

[P]O NBS, CH3CN O[P]O

NC

CH3

H2O O[P]O

NHAc

MW

Kochetkov amination(dimer formation)

α-anomer

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SYNAPS July 2011

N-Glycosides

OO

[P]O NBS, CH3CN O[P]O

NC

CH3

H2O O[P]O

HN

O

N OO

[P]O NBS, Et3SiOTf

O

N OOO

[P]O CH3CN O

N OO

[P]O N C CH3

H2O

O

N OO

[P]O HN

O

O

α-glycoside

β-glycoside

HO

O

O

O PhNHR

O

N OO

[P]O N

O

O NHR

O

O Ph

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SYNAPS July 2011

N-Glycosides

Glycosylasparagine Amino Acids

ON3

[P]O PPh3 , DCMor MeOH

[P]-Asp-O[P]

COOH

O HN

[P]O

O [P]-Asp-O[P]

OSO

[P]O PhTf2O, DCM

[P]-Asp-O[P]

CONHSiMe3

O HN

[P]O

O [P]-Asp-O[P]

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SYNAPS July 2010

Glycosylation Methods:Synthesis of 2-Deoxy-N-Glycosides

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SYNAPS July 2011

The Cycloaddition Approach to 2-Deoxy-N-Glycosides

Y

N O

SNPhthY

N OR

R

Y

N O

S

R

Y

O O

S

ORO

ROOR

N

SO

R

O

S N

ORRO

RO

OR

PhthN-SCl

?

α-imino-α’-oxothione

R = H, EDG

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SYNAPS July 2011

The Cycloaddition Approach to 2-Deoxy-N-Glycosides

OEt

O O

OEt

N OSO2Ph

OEt

HN O

SNPhth

SO2Ph

EtO

N

SO

SO2Ph

OOBn

BnOBnO

O

S NO

EtO

SO2Ph

OBn

BnOBnO

O

S NO

EtO

SO2Ph

OBnBnO

BnO

OBnO

OBn

BnO NS

OEtO

SO2Ph

PhthN-SCl

85 %

Base

87 %

71 %

OOBn

BnO

OBnO

OBnBnO

BnO

EtO

N

SO

SO2Ph

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SYNAPS July 2011

The Cycloaddition Approach to 2-Deoxy-N-Glycosides

EtOOBn

O O NHBoc

OEtO

OBnO NTs NHBoc

O

EtOOBn

O NTs NHBoc

OSNPhth

EtOOBn

O NTs NHBoc

OS

OOBnBnO

BnOO

S NTsO

EtO

OBnBnO

BnO

PhthNSCl

Base

NHBoc

OOBn

75 %

H H

92% - 2 steps 65% - 2 steps

HOOBn

O NHBoc

O

α-N-Galattohomoglutamate

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SYNAPS July 2011

Synthesis of Carbohydrate-Containing Natural Compounds

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SYNAPS July 2011

OHOOC

HO OHO

O

HO

NHAcO

GLYCOSAMINOGLYCANS

Glycosaminoglycans are unbranched polymers of alternating uronic acid and hexosamine residue

The extra cellular spaces, particularly those of connective tissues (cartilage,tendon, skin …) consist of collagen and elastin fibers embedded in a gel-like matrix known as ground substance.

Ground substances is composed largely of glycosaminoglycans also called mucopolysaccharides (solution of glycosaminoglycans are mucus-like)

O

O OOOC

OHO

HOHO

OSO3

O3SHN ORepeating unit ofHeparin

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SYNAPS July 2011

HEPARIN

• Heparin is a variable sulfated glycosaminoglycan that consists predominantly of alternating a-(1,4)-linked residues of L-iduronic acid and N-, O-di-sulfated glucosamine.• Heparin is not a constituent of connective tissue but occurs almost exclusively• In the intracellular granules of the mast cells that line artherial walls.• It inhibits clotting of blood• It is widely used to inhibit blood clotting in postsurgical patients• Heparin’s anticoagulant effect has been attributed to its binding to antithombin III(factor of blood clotting cascade)

• A pentasaccharidic fragment has been identified as the minimal effective structuralelement in heparin binding to antithrombin

O O O

OOC

OHO

OSO3HO

OSO3

O3SHNOH

OO

OSO3

O3SHNO3S

OO

OHHO

COOO

HO OHO

OSO3

O3SHN

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SYNAPS July 2011

Synthesis of Heparin Oligosaccharideby Seeberger

Alessandra BartolozziBoeringher, USA

O O O

OOC

OHO

OSO3HO

OSO3

O3SHNOH

OO

OSO3

O3SHNO3S

OO

OHHO

COOO

HO OHO

OSO3

O3SHN

α- glycosidecis-glycoside

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SYNAPS July 2011

Synthesis of Heparin Oligosaccharideby Seeberger

O OAcO

TBSOBnO

N3

O

NH

CCl3

MeO2CHOBnO

OBzO+

OAcO

TBSOBnO

N3

O OCO2Me

BnOOBz

O

TMSOTfCH2Cl2

- 78 °C - rt

α / β = 3 / 1 (57%)

ORO

TBSOBnO

N3

F +O

MeO2CHOBnO

OBzO

AgClO4 , SnCl2Et2O, MS 4A

0 °C - rtO

RO

TBSOBnO

N3

O OCO2Me

BnOOBz

O

R = Ac ; α / β = 7 / 1 (77%)α / β =5 / 1 (43%)R = Bn ;

R = AcR = Bn

Glucuronic Acid Acceptors

Stereoselective formationof cis-glycosides can not rely

on anchimeric assistance

Non-participatinggroup

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SYNAPS July 2011

Synthesis of Heparin Oligosaccharideby Seeberger

Iduronic Acid Acceptors

OAcO

TBSOBnO

N3

O

NH

CCl3

OAcO

TBSOBnO

N3

F

OOBn

MeO2C OTDS

OHOH

OOBn

MeO2C OTDS

OHOH

+

+

TMSOTfCH2Cl2

- 78 °C - rt

AgClO4 , SnCl2Et2O, MS 4A

0 °C - rt

OOBn

MeO2C OTDS

OHO

OAcO

TBSOBnO

N3

OOBn

MeO2C OTDS

OHO

OAcO

TBSOBnO

N3

completely α selective (47%)

completely α selective (30%)

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SYNAPS July 2011

Synthesis of Heparin Oligosaccharideby Seeberger

O

OO

OO

HO

Diacetone Glucofuranoside

O

OO

HOCO2Me

BnO

TFA> 90% O

MeO2C

OHOH

BnOHO

Glucuronic Acid1) Tf2O py2) LevONa 80 °C 80% (2 steps)

O

OO

LevOCO2Me

BnO

OMeO2COBn

OHOH

OHN2H4 , AcOH

py , 91%

TFA aq.90%

Iduronic Acid

C-5 inversion

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SYNAPS July 2011

Synthesis of Heparin Oligosaccharideby Seeberger

The conformation of the different acceptors suggested a possible explanationfor the different behaviour of glucuronic and iduronic acid acceptors.

O

OH

HOHO

OHOH1

4O

OH

OH OH

OHHO

41

D-Glucopyranose

O

OHHO

OH

OH

OH1

4

D-Idopyranose

OHO

HO OH

OHHO

41

O

OH

HOHO

OH

OH OOH

OH OH

OHHO

L-Idopyranose

4

1

1

4

4C1

4C1

4C1

1C4

1C4

1C4

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SYNAPS July 2011

OMeO2C

HOBnO

OHOH

4C1 C4 OH equatorial

Synthesis of Heparin Oligosaccharideby Seeberger

The conformation of the different acceptors suggested a possible explanationfor the different behaviour of glucuronic and iduronic acid acceptors.

OMeO2COBn

OHOH

OH

1C4 C4 OH axial

O

2

2SO depending on substituent on the ring

Glucuronic Acid

Iduronic Acid

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SYNAPS July 2011

OMeO2C

HOBnO

OHOH

OMe

CSADMF

OMe

CSADMF

O

MeO2COBn

OOH

O

O

MeO2COBn

OOH

O

48%

57%

+ furanosidic side product

furanosidic side product+

Conformationally constrainedGlucuronic Acid Acceptors

Synthesis of Heparin Oligosaccharideby Seeberger

OMeO2COBn

OHOH

OH

OMe

CSADMF

OMe

CSADMF

OMeO2COBn

OOH

O

OMeO2COBn

OOH

O

68%

56%

+ furanosidic side product

+ furanosidic side product

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SYNAPS July 2011

Synthesis of Heparin Oligosaccharideby Seeberger

OAcO

TBSOBnO N3

O

HNCCl3 O

MeO2COBn

OOH

O

RR

+O

AcO

TBSOBnO

N3

O

MeO2COBn

OO

O

RR

OAcO

TBSOBnO N3

O

HNCCl3

+ O

MeO2COBn

OOH

O

RR

OAcO

TBSOBnO

N3

O

MeO2COBn

OO

O

RR

OAcO

TBSOBnO

N3 O

OAcO

TBSOBnO

N3 O

H+

H+

OCO2Me

BnOOH

OH

OCO2Me

BnOOH

OH

Both glycosyl trichloroacetimidate andglycosyl fluoride resulted in the exclusivelyformation of α-linked disaccharides

Different protecting groups can be used

Glucuronic Acid Acceptors

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SYNAPS July 2011

Synthesis of Heparin Oligosaccharideby Seeberger

ORO

TBSORO N3

O

HNCCl3

Different protecting groups can be used

OOBn

MeO2C

OH

O

OR

R+

Locked Iuduronic Acid Acceptor

TBSOTf

MS 4ACH2Cl2-30 - rt> 90%

ORO

TBSORO

N3

OOBn

MeO2C O

OR

RO

CCl2HCOOH(60% aq)

ORO

TBSORO

N3

OOBn

MeO2C OH

OHO

80-90%

R = Ac, Bn

α- linked glycosides

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SYNAPS July 2011

Synthesis of Heparin Oligosaccharideby Seeberger

Oligosaccharide Assembly Using Disaccharide Modules

OAcO

ROBnO

N3 O OCO2Me

BnOOH

OH

(MCA)2OCH2Cl2DMAP

Py

MCA = monochloroacetate participating protective group, orthogonal(thiourea, DMF-py, rt, 24h)

OAcO

ROBnO

N3 O OCO2Me

BnOOMCA

OMCA

OAcO

ROBnO

N3 O OCO2Me

BnOOMCA

OH

BnNH2Et2O0 °C

OAcO

ROBnO

N3 O OCO2Me

BnOOMCA

ONH

CCl3

CCl3CNDBUCH2Cl20 °C

70-90%

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SYNAPS July 2011

Synthesis of Heparin Oligosaccharideby Seeberger

Oligosaccharide Assembly Using Disaccharide Modules

OAcO

TBSORO

N3

OOBn

MeO2C OH

OHO

Ac2OPyDMAP O

AcO

TBSORO

N3

OOBn

MeO2C OAc

OAcO

OAcO

TBSORO

N3

OOBn

MeO2C OH

OAcO

OAcO

TBSORO

N3

OOBn

MeO2C O

OAcO

BnNH2Et2O0 °C

CH2Cl20 °C

CCl3CNDBU

65-75%

CCl3

HN

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SYNAPS July 2011

Synthesis of Heparin Oligosaccharideby Seeberger

OAcO

ROBnO

N3 O OCO2Me

BnOOMCA

ONH

CCl3

OAcO

ROBnO

N3 O OCO2Me

BnOOMCA

O

Different participatingorthogonal protectinggroups: Lev, Alloc

Lev = levulinoylAlloc = allyloxycarbonate

O OHO

OAcO

HOBnO

N3 O OCO2Me

BnOOMCA

O

4-penten-1-olTMSOTfCH2Cl2

0 °C

• Temporary protecting group• Glycosidating agent (donor)• Conveniently used (handled)for attachment to protein orsurfaces

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SYNAPS July 2011

OAcO

TBSORO

N3

OOBn

MeO2C O

OAcO

CCl3

HNO

AcO

HOBnO

N3 O OCO2Me

BnOOMCA

O+

OAcO

OBnO

N3 O OCO2Me

BnOOMCA

O

O

AcOHORO

N3O

OBnMeO2C

AcOO

TMSOTf, CH2Cl2 - 25 °C

Tetrasaccharide

HFPy75-90%

Synthesis of Heparin Oligosaccharideby Seeberger

Poor reactive!

Hexasaccharide

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SYNAPS July 2011

Synthesis of Heparin Oligosaccharideby Seeberger

Oligosaccharide Assembly Using Trisaccharide Modules

OAcO

HOBnO

N3 O OCO2Me

BnOOLev

OOMeO2C

OBn

OAcTBDSO

O

HN

CCl3 +TMSOTf,CH2Cl2

- 25 °C93%

OAcO

BnO N3 O OCO2Me

BnOOLev

OOMeO2C OBn

AcOTBDSO

OOAcO

BnO N3 O OCO2Me

BnOOLev

OOMeO2C OBn

AcOTBSO

O HFPy

AcOHTHF82%

Orthogonal Protecting Group

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SYNAPS July 2011

Synthesis of Heparin Oligosaccharideby Seeberger

Oligosaccharide Assembly Using Trisaccharide Modules

OAcO

BnOBnO

N3 O OCO2Me

BnOOLev

ONH

CCl3

+ OAcO

HOBnO

N3

OTBSTMSOTf,CH2Cl2

- 25 °C63%

OAcO

BnOBnO

N3 O OCO2Me

BnOOLev

O OAcO

BnON3

OTBS

OAcO

BnOBnO

N3 O OCO2Me

BnOOLev

O OAcO

BnON3

O NH

CCl3

TBAFAcOH

CCl3CNDBU,CH2Cl2- 25 °C87% (2 steps)

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SYNAPS July 2011

Synthesis of Heparin Oligosaccharideby Seeberger

OAcO

BnO N3 O OCO2Me

BnOOLev

OOMeO2C OBn

AcOTBSO

O

OAcO

BnOBnO

N3 O OCO2Me

BnOOLev

O OAcO

BnON3

O NH

CCl3TMSOTf,CH2Cl2- 25 °C

62%

+

OAcO

BnOBnO N3 O

OCO2Me

BnO OLev

OO

AcO

BnO N3 O

O

AcO

BnON3 O O

CO2Me

BnOLevO

O

OMeO2C OBn

AcO

O

1)

2)

reduction (- N3)

deprotection

Et3NSO3

Py SO3, H2Osulfated hexasaccharide

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SYNAPS July 2011

Synthesis of the saccharidic core of human GPI anchor

Barbara RichichiUniversity of Florence

PNH: Paroxysmal nocturnal hemoglobinuria

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SYNAPS July 2011

Synthesis of the saccharidic core of human GPI anchor

O

O

O

HOHO

OOH

HOHO

OOHO

HO

OH

O OHO

OH

H2N OHO OH OH

OHO

OH

PHO

O O

OO

O

R

O

R

PO

OH

O NH2

P

Man

Man

Man

GlcN

Inos

P

LipLip

α(1 6)

α(1 2)

α(1 6)

α(1 4)

6

1

NH2

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SYNAPS July 2011

Synthesis of the saccharidic core of human GPI anchor

OOHOBn

BnOBnO

O

OBnOBnO

OBz

OAll

OOAcOBn

BnOBnO

O

OBnOBnO

OBz

OAll

OOAcOBn

BnOBnO

OH

OBnOBnO

OBz

OAll

O NHCl3C

CH2Cl2TMSOTf

CH2Cl2MeOH

AcCl

95%

80%Man-1

Man-2

Man-2

Man-1

O

O

OTIPS

BnOBnO

OAc

ONH

Cl3C

CH2Cl2TMSOTf

O

O

OTIPS

BnOBnO

OOBn

BnOBnO

O

OBnOBnO

OBz

OAll

OAc

83%

Man-3

Man-3

Man-2

Man-1

PdCl2

AcOH

NaOAc

H2O

Cl3CCN

CH2Cl2

DBU

94%70%

Man-3

Man-2

Man-1

O

O

OTIPS

BnOBnO

OOBn

BnOBnO

O

OBnOBnO

OBz

ONH

Cl3C

OAc

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SYNAPS July 2011

Synthesis of the saccharidic core of human GPI anchor

O

O

OTIPS

BnOBnO

OOBn

BnOBnO

OOBnO

BnO

OBn

O OBnO

OBn

N3OBnO OBnOBn

OBnAllO

OBn Man-2

Man-1

GlcN

Man-3

Inos

Man-3

Man-2

Man-1

O

O

OTIPS

BnOBnO

OOBn

BnOBnO

O

OBnOBnO

OBz

ONH

Cl3C

OAcGlcN

InosHO OBnO

BnO

N3O

BnO OBnOBnOBnAllO

CH2Cl2TMSOTf- 40°C

80%

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SYNAPS July 2011

O

RCOHN

OHHO OH

O OH

OH+ O

Me2NOMc

SN

N AgOTfCH2Cl2/ PhMe

25 °C36 %, β anomer

S-pyrimidyl D-desosaminideO

RCOHN

OHHO OH

O OH

O

Mc = methoxycarbonyl

OMcO NMe2

O

SPy

AcO

MeO

Pb(ClO4)2MeCN25 °C

1)

2) MeOH37%, overall

α-anomer

O

RCOHN

OHHO OH

O O

OOMcO NMe2

O

MeO

OAc

Na-HgMeOH75%

O

H2N

OHHO OH

O O

OOHO NMe2

O

MeO

OH

O-Glycosides AntibioticsSynthesis of Erythromycin A by Woodward

C-2’ neighbouringparticipation

14-membered macrolide lactone

L-cladinose(acid sensitive)

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SYNAPS July 2011

O

H2N

OHHO OH

O O

OOHO NMe2

O

MeO

OH

NCSPy

O

ClHN

OHHO OH

O O

OOHO NMe2

O

MeO

OH

O

OHHO OH

O O

OOHO NMe2

O

MeO

OH

AgFHMPA

O

OHHO OH

O O

OOHO NMe2

O

MeO

OH

O

NH

H2O40%

(3 steps)

O-Glycosides AntibioticsSynthesis of Erythromycin A by Woodward

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SYNAPS July 2011

O-Glycosides AntibioticsSynthesis of Erythromycin A by Toshima-Tatsuta

… ten years later ….

O

OH

OHHO OH

O OH

OH

(9S)-9-Dihydroerythronolide A

MeOOMe

OMeCSA, CH2Cl2

87% O

OH

OHHO OH

O O

O

OMe

OMePPTSCH2Cl2100%

O

O

OHO OH

O O

O

OMe

H2, Pd(OH)2EtOAc, 95%

O

O

OHO OH

O OH

OH

O

OMcMe2N SPym

AgOTf, MS 4A

CH2Cl2, 25 °C4 h, 63%β-anomer

O

O

OHO OH

O OH

OOMcO NMe2

mCPBACH2Cl2100%

O

O

OHO OH

O OH

OOMcO N(O)Me2

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SYNAPS July 2011

O

O

OHO OH

O OH

OOMcO N(O)Me2

O

S

OMeBnO

Me SPhO

O

OHO OH

O

OOHO N(O)Me2

O

S

MeOOBn

MeONIS, TfO, MS 4A

CH2Cl2, 35 °C, 10 min90 %, α-anomer

O

OH

OHHO OH

O

OOHO NMe2

O

MeO

OHMe

O

AcOH-H2O(50 %) 66 %

H2 / Raney Ni EtOH - 54%

O

O

OHHO OH

O

OOHO N(O)Me2

O

MeO

OHMe

O

O

OH

OHHO OH

O

OOHO NMe2

O

MeO

OHMe

O 1) mCPBA 99 %2) (nBu3Sn)O Br2, 58 %

H2 / Raney Ni EtOH - 84%

O-Glycosides AntibioticsSynthesis of Erythromycin A by Toshima-Tatsuta

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SYNAPS July 2011

O-Glycosides AntibioticsSynthesis of Avermectin B1a by Ley

OMe OHHO

MeO

OMe OAcAcO

MeO

OMe OAcHO

MeO+

OMe OHAcO

MeO

LiBHEt3THF 95%

CDI, AcOH

CH2Cl293%

CDI

CH2Cl2

CDI = 1,1-carbonyl diimidazole

OMe OAcO

MeO

O

N N

OMe OAcO

MeO

O

N N OMe OAcHO

MeO+

AgClO4, THF50 °C, 45 min

73%α/β = 5.6/1

OMeAcO

MeO

OOMe OAc

MeO

LiBHEt3THF 95%

OMeAcO

MeO

OOMe OH

MeOOMe

AcOMeO

OOMe

MeO

O

S

N NIm2C=S

THF

57%

1 : 1Oleandrose

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SYNAPS July 2011

O-Glycosides AntibioticsSynthesis of Avermectin B1a by Ley

OMeAcO

MeO

OOMe

MeO

O

S

N N

O O

MeMe

Me

O

Me

O

O

HO

Me

MeOAc

H

OH

H

+

AgClO4CaCO3

THF / PhMert, 10 min

80%α/β = 4/1

OMeAcO

MeO

O OMe

MeO

O O

MeMe

Me

O

Me

O

O

O

Me

MeOAc

H

OH

H

OMeHO

MeO

O OMe

MeO

O O

MeMe

Me

O

Me

O

O

O

Me

MeOH

H

OH

H

LiBHEt3THF

90%

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SYNAPS July 2011

O-Glycosides AntibioticsSynthesis of Avermectin B1a by Nicolaou

O

O

SPh

F

MeHO

MeO

MeTBSO

MeO

+SnCl2 AgClO4

Et2O, MS 4A- 15 °C- rt, 30 min65%, α-anomer

O

OMe

TBSOMeO

O

SPh

MeMeO

O

OMe

TBSOMeO

O

F

MeMeO

DAST- NBSCH2Cl2

85%

+

O O

MeMe

Me

O

Me

O

O

HO

Me

MeOTBS

H

OH

HSnCl2 - AgClO4Et2O, MS 4A0 °C, 16 h

62%, α-anomer

O O

MeMe

Me

O

Me

O

O

O

Me

MeOTBS

H

OH

HO

OMe

TBSOMeO

OMeO

Me

TBAFTHF89%

O O

MeMe

O

Me

O

O

O

Me

MeOH

H

OH

HO

OMe

HOMeO

OMeO

Me

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SYNAPS July 2011

O-Glycosides AntibioticsSynthesis of Avermectin B1a by Hanessian

OMeHO

MeO

O OMe

MeO

O O

MeMe

Me

O

Me

O

O

O

Me

MeOH

H

OH

H

OMeTBSO

MeO

OOMe

MeO

S NOMe

TBSOMeO

O OMe

MeO

O O

MeMe

Me

O

Me

O

O

O

Me

MeOTBS

H

OH

H

O O

MeMe

Me

O

Me

O

O

HO

Me

MeOTBS

H

OH

H

+ AgOTf, CH2Cl2MS 4A, rt, 20 min

35%α anomer

HF Py64%

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SYNAPS July 2011

C-Glycosides AntibioticsSynthesis of Vineomycinone B2 by Suzuki

O

F

BzOBzO

HO OMe

MeO OMe

+ OBzOBzO

HO MeO

MeO OMe

OTBSOTBSO

MeO MeO

MeO OMe

Cp2HfCl2 / AgClO4CH2Cl2

- 78 °C- 0 °C86%

β anomer1) NaH, Me2SO4 THF, 100%2) NaOH, MeOH/H2O3) TBSOTf, lutidine CH2Cl2 , 96%

t-BuOK, n-BuLiMe2SnCl

THF64%

OTBSOTBSO

MeO MeO

MeO OMe

SnMe2

OHCOBn

MeLi PhMe 84%

OTBSOTBSO

MeO MeO

MeO OMe OR

OBn

R = HR = Bz

BzCl, DMAPPy, 94%

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SYNAPS July 2011

OTBSOTBSO

MeO MeO

MeO OMe OBz

OBn

1) CAN MeCN/ H2O

2) DDQ CH2Cl2 - pH 8 69% overall

OTBSOTBSO

MeO O

O OMe OBz

OH

Na2S2O41N NaOHdioxane / H2O92%

OTBSOTBSO

MeO O

O OMe

OHO3 , MeOH

OTBSOTBSO

MeO O

O OMe

CO2MeOH

Ac2O, Et3N

BBr3 , CH2Cl2 90%

OHOHO

MeO O

O OMe

CO2MeOH

C-Glycosides AntibioticsSynthesis of Vineomycinone B2 by Suzuki

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SYNAPS July 2011

Synthesis of Digitoxin by McDonald

OTBSO

TBSO+

OBz

H

TBSOHO

OTBSO

TBSO

H

OBz

TBSOO

OTBSO

TBSO

H

OH

TBSOOOO

TBSO

OTBSO

OTBS

OO

TBSO

OHO

OH

OO

TBSO

OAcO

OAc

Ph3P - HBrPhMe

88%α / β = 1/ 32

DIBAL CH2Cl2 99%

W(CO)6DABCO

THF, 65 °Chv (350 nm)

96%

OO

TBSO

OAcO

OAc

H

OBz

TBSOO

OBz

H

TBSOHO

TBAF,THF

Ac2O, Et3NDMAP, CH2Cl288% (2 steps)

+

Ph3P - HBrPhMe

71%α / β = 1/ 99

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SYNAPS July 2011

Synthesis of Digitoxin by McDonald

OO

TBSO

OHO

OHO O

TBSO

O O

OH

H

H

H

+

OO

TBSO

OAcO

OAcO O

TBSO

O

W(CO)6DABCOTHF, 65 °Chv (350 nm)

OO

TBSO

OHO

OH

H

OH

TBSOO

DIBALCH2Cl2 98%OO

TBSO

OAcO

OAc

H

OBz

TBSOO

Ac2O, Et3NDMAP, CH2Cl281% (2 steps)

O O

OH

H

H

HHO

OO

TBSO

OAcO

OAcO O

TBSO

O O

OH

H

H

HOO

OH

OHO

OHO O

OH

O

Ph3P - HBr CHCl3, 82% α / β = 2 / 3

1) (NH4)HF2 DMF , NMP2) MeONa , MeOH 40% (2steps)

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SYNAPS July 2011

Polo ScientificoUniversity of Florence

Dipartimento di Chimica

“Ugo Schiff”

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SYNAPS July 2011

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SYNAPS July 2009

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Thank

you fo

r the a

ttentio

n !!!!

Thank

you fo

r the a

ttentio

n !!!!