10 Mar 2004 ... NH2. Amino Acid. Polypeptide (linear). Linhorst, T. K. Essentials of Carbohydrate
Chemistry and Biochemistry, Wiley-VCH: Weinheim, 2003.
New Methodologies for Oligosaccharide Synthesis
Man-Kit Lau Department of Chemistry Michigan State University
March 10, 2004
Outline
1.
Introduction
2.
Solid Phase Approach: Automated Oligosaccharide Synthesizer
3.
Solution Phase Approach: OptiMer One-Pot Oligosaccharide Synthesis
4.
Summary
Outline
1.
Introduction
2.
Solid Phase Approach: Automated Oligosaccharide Synthesizer
3.
Solution Phase Approach: OptiMer One-Pot Oligosaccharide Synthesis
4.
Summary
What are Oligosaccharides?
O H HO H H
H
OH
OH H OH OH CH2OH
O
HO HO
OH HO
D-Glucose
OH HO HO
O OH HO
HOW?
O HO
O OH HO
O HO
O OH HO
Maltotriose
Lehninger, A. L.; Nelson, D. L.; Cox, M. M. Principles of Biochemistry, Worth Publishers, Inc., 1993.
Traditional View of Oligosaccharides
Energy Storage Structural Scaffold
Starch
Plant
Animal
Starch
Glycogen
Cellulose
Chitin
Cellulose
Lehninger, A. L.; Nelson, D. L.; Cox, M. M. Principles of Biochemistry, Worth Publishers, Inc., 1993.
Cell Surface Glycoproteins
cell surface glycoproteins act as protein ligands for cell-cell recognition
Bertozzi, C. R.; Kiessling, L. L. Science 2001, 291, 2357. Sears, P.; Wong, C.-H. Angew. Chem. Int. Ed. 1999, 38, 2300.
Synthetic Chemistry is Key to Studying Glycobiology Biopolymer
Primary Synthetic Methods
DNA
1. Automated nucleic acid synthesis 2. Polymerase chain reaction (PCR)
Protein
1. Automated peptide synthesis 2. Overexpression system 3. Even unnatural proteins can be made now
Oligosaccharide
1. Isolation from natural sources 2. Enzymatic synthesis 3. Chemical synthesis
Protein and DNA Synthesis: Template Driven Glycoprotein Synthesis: Post-Translational Attachment
Koeller, K. M.; Wong, C.-H. Chem. Rev. 2000, 100, 4465.
Glycoprotein Biosynthesis
Structural homogeneity is difficult to achieve.
Bertozzi, C. R.; Kiessling, L. L. Science 2001, 291, 2357.
Possible Routes to Homogeneous Oligosaccharides
Oligosaccharides
¥
Enzymatic Synthesis
Natural Sources
Chemical Synthesis
Ultimate Goal: General and Efficient Synthesis of Oligosaccharides
Koeller, K. M.; Wong, C.-H. Chem. Rev. 2000, 100, 4465. Plante, O. J.; Palmacci, E. R.; Seeberger, P. H. Science 2001, 291, 1523. Sears, P.; Wong, C.-H. Science 2001, 291, 2344.
Oligosaccharides Synthesis: A Big Challenge
“ There are no universal reaction conditions for oligosaccharides synthesis” - Hans Paulsen
Paulsen, H. Angew. Chem. Int. Ed. Engl. 1982, 21, 155.
Structural Complexity of DNA and Peptides
Monomeric Building Blocks
(HO)2P O Nucleotide nucleotide
O
Oligomeric Biomolecules
base
DNA (linear)
O OH
Amino Acid amino acid
R
COOH NH2
Polypeptide (linear)
Linhorst, T. K. Essentials of Carbohydrate Chemistry and Biochemistry, Wiley-VCH: Weinheim, 2003.
Structural Complexity of Oligosaccharides
Monomeric Building Blocks
pyranoside
OH HO HO HO
Oligomeric Biomolecules
OH HO HO HO OH HO
O OH
HO HO
O
a O O HO
HO
O
O
OH
b Linear and branched!
Linhorst, T. K. Essentials of Carbohydrate Chemistry and Biochemistry, Wiley-VCH: Weinheim, 2003.
Possible Isomers Among Biopolymers
Oligomer
Oligonucleotides
Oligopeptides
Oligosaccharides
Dimer
2
2
20
Trimer
6
6
720
Tetramer
24
24
34,560
Pentamer
120
120
2,144,640 2,144,640
Linhorst, T. K. Essentials of Carbohydrate Chemistry and Biochemistry, Wiley-VCH: Weinheim, 2003.
Selective Protection and Deprotection Steps 1o hydroxyl anomeric hydroxyl O
OH HO HO
H HO H H
O OH
OH
H OH H OH aldehyde OH CH2OH
3 x 2o hydroxyl OH HO HO
O OH H2N
1o amine
glucosamine
Selective Protection and Deprotection Steps
OH HO
1. ClCH2C(O)Cl DMF, -50oC, 55% 2. BzCl, pyridine, 90%
O
HO
OMCA BzO
OCH3
O
BzO
OH methyl-D-glucopyranoside
OCH3 OBz
OH BzO
thiourea CH2Cl2
O
BzO
OCH3 OBz
O
O
Ac =
Bz =
O
MCA = monochloroacetyl =
Cl
Linhorst, T. K. Essentials of Carbohydrate Chemistry and Biochemistry, Wiley-VCH: Weinheim, 2003.
Glycosidic Bond Formation OR RO RO
activator (Lewis Acid)
O L
OR RO RO
OR O
O
RO RO
RO RO
RO oxonium ion
glycosyl donor
glycosyl acceptor
R'
O
H
OR O
RO RO
OR' RO
NH L= R=
Br , O
SR ,
O
,
O
CCl3
O ,
etc.
O ,
,
etc.
O O
Classical Approaches Towards Oligosaccharide Synthesis
1.
Chemical Synthesis: eg. Glycosyl halide coupling. OAc
OAc ROH, Ag2CO3, CH2Cl2
O
AcO AcO
Br
-AgBr
AcO
O
AcO AcO
OR AcO
-AgBr anchimeric assistance OAc AcO AcO
OAc O
AcO AcO
O
O
O
O
R O H
O
Linhorst, T. K. Essentials of Carbohydrate Chemistry and Biochemistry, Wiley-VCH: Weinheim, 2003.
Classical Approaches Towards Oligosaccharide Synthesis
2.
Enzymatic Synthesis: eg. Synthesis of the core trisaccharide of N-linked glycoprotein.
OH HO HO
OH O OpNP
b-mannosidase from Helix pomatia (edible snails)
+ OH HO HO
O O NHAc HO
OH
OH HO HO
OH
OH O O HO
OH
O O NHAc HO
O OH NHAc
O OH NHAc
20% yield
pNP: para-nitrophenyl
Scigelova, M.; Singh, S.; Crout, D. H. G. J. Chem. Soc., Perkin Trans. 1 1999, 7, 777. Koeller, K. M.; Wong, C.-H. Chem. Rev. 2000, 100, 4465.
Outline
1.
Introduction
2.
Solid Phase Approach: Automated Oligosaccharide Synthesizer
3.
Solution Phase Approach: OptiMer One-Pot Oligosaccharide Synthesis
4.
Summary
Solid Phase: Automated Oligosaccharide Synthesizer
The first automated oligosaccharide synthesizer based on Applied Biosystems Inc. Model 433A Peptide synthesizer
Plante, O. J.; Palmacci, E. R.; Seeberger, P. H. Science, 2001, 291, 1523.
Solid Phase Synthesis of Oligosaccharides OP4 O
O 1
P1O
OP4 O
Deprotection OP3
O 1
Coupling
P1O
OP2
OP4
OH
O P1O
OP2
O 1
OP8
O OP2 P5O
O 2 OP7 OP6
Deprotection OP4 O P1O
...
O 1
OP4 O
OP8 O
OP2 P5O
O 2 O OP6 P9O
OP12 O 3
Coupling
P1O
O 1 O OP2 P5O
OP11 OP10
=
H2C HC n
P = protecting group Fréchet, J. M. J.; Schuerch, C. J. Am. Chem. Soc. 1971, 93, 492.
OP8 O 2 OH OP6
First Solid Phase Synthesis of Disaccharide
OR BnO BnO
OH O
BnO BnO
=
BnO
OR O Br
BnO
O
n
BnO
75% yield
O O BnO
O
O
R=
HC
O
BnO BnO
OH
H2C
BnO BnO
Bn = NO2
Fréchet, J. M. J.; Schuerch, C. J. Am. Chem. Soc. 1971, 93, 492.
Solid Phase Synthesis of Oligosaccharides Using Glycal Assembly HO
O O
O
O O
O
P3O
O P1O
OP2 glycal
O
OP4
O P1O
O
P3O OH
P1O
OP2 1,2-epoxyglycal
O
OP2
O
OP4
[O] O
P5O
...
O O
P3O OH
P1O OP2
=
H2C
O
P6O O
O
O
P6O O OH
OP4
P5O
O
OH
O P3O OH
P1O OP2
O O OP4
Si(iPr)2
HC n
P = protecting group
Randolph, J. T.; McClure, K. F.; Danishefsky, S. J. J. Am. Chem. Soc. 1995, 117, 5712.
Tetrasaccharide Synthesis Using Glycal Assembly O O
O O
O O
O O
O
O
CH2Cl2
O
OH
O
O O
O
O
O
O
ZnCl2, THF
O
O
O
O
O HO O O
O
O
O
O
O
O O
O
1.
O HO O
OH
O O
Bn =
O HO O
=
H2C
Si(iPr)2
HC n
2. BnO BnO
O O O
O
, CH2Cl2
O
repeat O
O
O O
O
O
O HO O
O O O
O
O HO O O
O
O
ZnCl2, THF
O HO BnO BnO
O
74% overall yield
Randolph, J. T.; McClure, K. F.; Danishefsky, S. J. J. Am. Chem. Soc. 1995, 117, 5712.
Choice of Glycosylating Agents
OLev
OLev
1. DMDO 2. HOP(O)(OBu)2 3. PivCl, DMAP
O
BnO BnO
BnO BnO
O O PivO
P(OBu)2 O
OBn AcO BnO BnO
K2CO3, Cl3CCN
O OH
BnO BnO
OBn AcO
O O
CCl3 NH
O
Ac =
N
Bn =
Piv =
DMAP =
O
O
tBu
Lev =
N
O O
Plante, O. J.; Andrade, R. B.; Seeberger, P. H. Org. Lett. 1999, 1, 211. Schmidt, R. R. Angew. Chem. Int. Ed. Engl. 1986, 25, 212.
The Octenediol Linker 1. TMSOTf 2.
OLev
BnO BnO HO Cl
BnO
O O PivO
OBn
BnO
P(OBu)2
O
O
PivO
O
O
Merrifield's resin
O
H2C CH2 Cl Cl
Merrifield's resin =
1. NBS
O OR
BnO BnO
2. ROH
PivO
H2C Cl
HC
Ru PCy3
OLev
OLev BnO BnO
PCy3 Ph
NBS = O
Br N
O O PivO
O O
Lev =
O
Piv =
O O
tBu
Cy =
n
Andrade, R. B.; Plante, O. J.; Melean, L. G.; Seeberger, P. H. Org. Lett. 1999, 1, 1811.
Automated Solid Phase Synthesis of Protected b-Phytoalexin Elicitor (PE) OLev
OBn BnO BnO
O
Lev =
BnO
O O PivO BnO BnO OBn
O O
O
Piv =
O BnO O
tBu
BnO BnO
O O PivO O BnO O
BnO
O O PivO BnO BnO
O O PivO
Bn =
Plant glucan oligosaccharide. Induce plant to produce antibiotic phytoalexin.
Plante, O. J.; Palmacci, E. R.; Seeberger, P. H. Science 2001, 291, 1523.
Automated Solid Phase Synthesis of Protected b-Phytoalexin Elicitor (PE) OH O
BnO BnO
O PivO
O
HO O
Coupling TMSOTf
Deprotection H2NNH2
OLev
3 equiv. O
BnO BnO
O PivO
P(OBu)2 O
O
Lev =
OLev BnO BnO
O O PivO
O
O O
O
Piv = Bn =
Plante, O. J.; Palmacci, E. R.; Seeberger, P. H. Science 2001, 291, 1523.
tBu
Automated Solid Phase Synthesis of Protected b-Phytoalexin Elicitor (PE) OH OH
OBn BnO BnO
BnO OBnO O BnO BnO
O O
OO PivO PivO BnO O BnO
O O PivO
O
Coupling TMSOTf
Deprotection H2NNH2
10 equiv. BnO BnO
O BnO O BnO
O O PivO
O BnO O BnO
P(OBu)2 O
O
OLev
OBn BnO BnO
OLev
OBn
Lev =
O PivO BnO BnO
O
O
O
O O PivO
O
Piv =
O
Bn =
Plante, O. J.; Palmacci, E. R.; Seeberger, P. H. Science 2001, 291, 1523.
tBu
Automated Solid Phase Synthesis of Protected b-Phytoalexin Elicitor (PE) OH
O BnO OBn BnO BnO OBn OPivO BnO O O BnO BnO BnO O BnO BnO BnO
OH O
O
O O PivO O BnO PivO BnO BnO BnO
O
O PivO PivO
O
O O O
Coupling TMSOTf
Deprotection H2NNH2
OLev
10 equiv. O
BnO BnO
O PivO
P(OBu)2 O
OLev BnO BnO OBn BnO BnO
O
O
Lev =
O PivO O BnO O
BnO
O
O
O PivO BnO BnO
O
Piv =
O O O PivO
O
Bn =
Plante, O. J.; Palmacci, E. R.; Seeberger, P. H. Science 2001, 291, 1523.
tBu
Automated Solid Phase Synthesis of Protected b-Phytoalexin Elicitor (PE) OH OLev
OBn BnO BnO
O O BnO O BnO O O BnO O PivO OBn PivO O BnO O BnO O BnO BnO O O O BnO BnO PivO PivO OBn BnO O BnO O BnO O BnO O BnO O O PivO O BnO PivO BnO BnO BnO
O O PivO
Cleavage Cl
PCy3 Ph
Ru H2C Deprotection Cl
Coupling TMSOTf
CH2
PCy3
BnO BnO
O BnO O BnO
OLev
OBn BnO BnO
OLev
OBn
10 equiv. O BnO O BnO
O O PivO
P(OBu)2 O
O PivO BnO BnO OBn BnO BnO
O
O
O
Lev =
O PivO O BnO O
BnO
O
O
O PivO BnO BnO
O
Piv =
O O O PivO
O
Bn =
Plante, O. J.; Palmacci, E. R.; Seeberger, P. H. Science 2001, 291, 1523.
tBu
Coupling Cycle For Phosphate Donors Step Function 1 2 3 4 5 6 7 8 9 10 11 12
Couple Wash Couple Wash Wash Wash Deprotection Wash Wash Wash Wash Wash
Reagent
Time/min
5 equiv. donor and 5 equiv. TMSOTf CH2Cl2 5 equiv. donor and 5 equiv. TMSOTf 1:9 (MeOH : CH2Cl2) THF 3:2 (pyridine : acetic acid) 2 x 20 equiv. H2NNH2 3:2 (pyridine : acetic acid) 1:9 (MeOH : CH2Cl2) 0.2 M acetic acid in THF THF CH2Cl2
30 6 30 4 4 3 80 3 4 4 4 6
Each cycle: 3 hours
Plante, O. J.; Palmacci, E. R.; Seeberger, P. H. Science 2001, 291, 1523.
Solid Phase Synthesis of Protected b-Phytoalexin Elicitor OTBDPS
OH NO2
O
BzO BzO
O
BnO HO
a
BzO O
O
b
O BzO BzO BzO
O
SPh
O
AcO AcO
OAc
AcO
O BzO
, DMTST, then Et3N
BzO BzO
SPh
O OBz
O
BzO BzO OAc
, DMTST, then HF/pyr.
AcO AcO
O BzO O
O BnO O
O BzO BzO BzO
AcO
SPh
OAc
, DMTST, then HF/pyr.
Si(Ph)2(tBu)
O
Fmoc =
AcO AcO
O
Me OTf DMTST = Me S S Me
O
AcO AcO OAc
AcO AcO
O AcO O BnO O
AcO
O BzO BzO BzO OAc AcO AcO
O
AcO O
O BnO O
O BzO BzO BzO OAc
AcO
O
AcO AcO
O BzO O BnO O
AcO
O
O O BzO O BnO O
AcO
O O
BzO BzO BzO
O BzO BzO BzO
O BzO
O
hv
O
NO2
O
O
AcO AcO OAc
OAc
TBDPS =
O BzO
c
OH
OTBDPS
(c)
NO2
O
O
OAc
(b)
O BzO BzO BzO
O
O OBz
O
O BnO O
AcO AcO
NO2
OTBDPS BnO (a) FmocO
OH
OAc
NO2
O O BzO
O
O OAc BzO
20% overall yield
Nicolaou, K. C.; Winssinger, N.; Pastor, J.; DeRoose, F. J. Am. Chem. Soc. 1997, 119, 449.
Automated vs. Non-Automated Syntheses OAc
OLev
OBn BnO BnO
O BnO O BnO
O O PivO BnO BnO OBn BnO BnO
AcO AcO
O O PivO O BnO O
BnO
O
AcO AcO OAc
O O PivO BnO BnO
O O PivO
O AcO O BnO O
AcO
O O BzO BzO BzO OAc AcO AcO
O O BzO O BnO O
AcO
O O BzO BzO BzO
O OAc BzO
automated (Seeberger)
non-automated (Nicolaou)
automated
labor intensive
10 machine hours
122 reaction hours
80% yield
20% yield
Plante, O. J.; Palmacci, E. R.; Seeberger, P. H. Science 2001, 291, 1523. Nicolaou, K. C.; Winssinger, N.; Pastor, J.; DeRoose, F. J. Am. Chem. Soc. 1997, 119, 449.
Other Protected Oligosaccharides Synthesized with Automated Synthesizer Approach BnO BnO
OBn OAc O
n = 3, 74% yield (90% average yield per unit) n = 5, 42% yield (84% average yield per unit) n = 8, 34% yield (87% average yield per unit)
OBn O
BnO BnO
BnO BnO
O
OBn O
BnO BnO
n
O
OBn O
O
O
50% yield (84% average yield per unit)
OBn O
BnO BnO OBn BnO
polymannoside
O
OBn OAc O
O OPiv BnO
BnO
Leishmania tetrasaccharide O O
O
TCAHN =
N H O
CCl3
BnO OBn BnO
Ac =
HO O
O
Piv =
O
O TCAHN OBn
tBu
PivO
OPiv
OBn
O
O
O
12.6% yield (66% average yield per unit)
BnO OBn
OBn
O
PivO
O BnO
O HO O PivO
Lewisx pentasaccharide
Bn =
Plante, O. J.; Palmacci, E. R.; Seeberger, P. H. Science 2001, 291, 1523. Hewitt, M. C.; Seeberger, P. H. Org. Lett. 2001, 3, 3699. Love, K. R.; Seeberger, P. H. Angew. Chem. Int. Ed. 2004, 43, 602.
How About More Complex Molecules? OH OH HO AcHN
OH
HO2C O
OH
O
O HO
O
O
HO
HO
O
OR NHAc
O OH HO
HO
Sialyl Lewisx tetrasaccharide 4% overall yield in 8 steps (Denishefsky and Wong, 1992)
HO OH
HO OH
O
O HO
O
O
O AcNH
O OH HO
HO
OH OH
O O HO
HO2C
O HO
O OR HO
O HO HO
OH HO NHAc
Fucosyl GM1 5% overall yield in 15 steps (Denishefsky, 1999)
Danishefsky, S. J.; Gervay, J.; Peterson, J. M.; McDonald, F. E.; Koseki, K.; Oriyama, T.; Griffith, D. A.; Wong, C.-H.; Dumas, D. P. J. Am. Chem. Soc. 1992, 114, 8329. Allen, J. R.; Danishefsky, S. J. J. Am. Chem. Soc. 1999, 121, 10875.
Outline
1.
Introduction
2.
Solid Phase Approach: Automated Oligosaccharide Synthesizer
3.
Solution Phase Approach: OptiMer One-Pot Oligosaccharide Synthesis
4.
Summary
Solution Phase: OptiMer Programmed One-Pot Oligosaccharide Synthesis
Zhang, Z.; Ollmann, I. R.; Ye, X.-S.; Wischnat, R.; Baasov, T.; Wong, C.-H. J. Am. Chem. Soc. 1999, 121, 734.
The “Armed - Disarmed” Concept Armed
Disarmed
React Faster
React Slower
HO
HO O
O
HO
L
O activator
+ HO
HO O
+
O O
O L
L
L
Mootoo, D. R.; Date, V.; Fraser-Reid, B. J. Am. Chem. Soc. 1988, 110, 2662. Linhorst, T. K. Essentials of Carbohydrate Chemistry and Biochemistry, Wiley-VCH: Weinheim, 2003.
Protecting Groups Control
HO
HO O
O L
EDG
activator
+ HO
HO O
EWG
HO
EDG
O EDG
+
O O
O L
EWG
L
EWG
EDG = electron donating group EWG = electron withdrawing group
Mootoo, D. R.; Date, V.; Fraser-Reid, B. J. Am. Chem. Soc. 1988, 110, 2662. Linhorst, T. K. Essentials of Carbohydrate Chemistry and Biochemistry, Wiley-VCH: Weinheim, 2003.
L
Disaccharide Synthesis Using Protecting Groups Control OBn
armed
OBn
O
BnO BnO
O BnO
NBS
BnO BnO
O BnO BzO BzO
+ OH
disarmed
62% yield a:b=1:1
O
O O BzO
O
BzO BzO
O BzO
OH
Br N
NBS = O O
Bz =
O
BzO BzO
O
is NOT formed O
BzO BzO BzO
O O BzO
Bn =
Mootoo, D. R.; Date, V.; Fraser-Reid, B. J. Am. Chem. Soc. 1988, 110, 2662.
Disaccharide Synthesis Using Protecting Groups Control
Br Br OBn BnO BnO
O O
O BnO
N
O
Br
OBn
O
O
BnO BnO
O
BnO BnO
OBn
O BnO
BnO
HO BzO BzO
OBn BnO BnO O
Bz =
O
O O BzO
O BnO BzO BzO
O O BzO
Bn =
Mootoo, D. R.; Date, V.; Fraser-Reid, B. J. Am. Chem. Soc. 1988, 110, 2662.
Anomeric Reactivity Control
HO
HO O
O
HO
L1
O activator
+ HO
HO O
+
O O
O L2
L2
L2
L1 is better leaving group than L2
Mootoo, D. R.; Date, V.; Fraser-Reid, B. J. Am. Chem. Soc. 1988, 110, 2662. Linhorst, T. K. Essentials of Carbohydrate Chemistry and Biochemistry, Wiley-VCH: Weinheim, 2003.
One-Pot Synthesis of Protected Ciclamycin O S
O S +
O O
less reactive
+
O
TMSO
S
OMe
OBn
O HO
most reactive
0.05 equiv. TfOH -78oC
OBn
least reactive
S O S
O +
O
O OBn O
O HO
OBn
S
Bn = O
-70oC
O OBn O O OBn O
Ciclamycin Ciclamycin
25% overall yield
O
O S
OMe
>
S
O
Raghavan, S.; Kahne, D. J. Am. Chem. Soc. 1993, 115, 1580.
>>
S
Strategy for Sequential One-Pot Linear and Branched Oligosaccharides Synthesis
O X
O X
HO
O X
HO
less reactive
O OR
HO
least reactive
reducing end
O O
O O
most reactive donor
O O
O OR
O O O X most reactive donor
HO less reactive
O O X
HO reducing end
O OR
O O
O O O
O OR
Zhang, Z.; Ollmann, I. R.; Ye, X.-S.; Wischnat, R.; Baasov, T.; Wong, C.-H. J. Am. Chem. Soc. 1999, 121, 734.
OptiMer Database of Thioglycosyl Donors
Number in bracket represents the Relative Reactivity Value (RRV)
Ritter, T. K.; Mong, K.-K. T.; Liu, H.; Nakatani, T.; Wong, C.-H. Angew. Chem. Int. Ed. 2003, 42, 4657.
OptiMer Database of Thioglycosyl Donors
Zhang, Z.; Ollmann, I. R.; Ye, X.-S.; Wischnat, R.; Baasov, T.; Wong, C.-H. J. Am. Chem. Soc. 1999, 121, 734.
OptiMer Database of Thioglycosyl Donors
Ye, X.-S.; Wong, C.-H. J. Org. Chem. 2000, 65, 2410.
OptiMer Database of Thioglycosyl Donors
Ritter, T. K.; Mong, T. K.-K.; Liu, H.; Nakatani, T.; Wong, C.-H. Angew. Chem. Int. Ed. 2003, 42, 4657.
Relative Reactivity in Competitive Reactions
O SR
donor (D0)
O product (Dt) OMe NIS
HPLC analysis
MeOH (5eq.) O SR
reference (R0)
O reference OMe product (Rt)
OAc AcO
reference compound =
AcO AcO
O STol
NIS = O
I N
O
Zhang, Z.; Ollmann, I. R.; Ye, X. -S.; Wischnat, R.; Baasov, T.; Wong, C.-H. J. Am. Chem. Soc. 1999, 121, 734.
Relative Reactivity in Competitive Reaction
RRV =
kD kR
=
In([Dt]/[D0]) In([Rt]/[R0])
OAc
R0
AcO
The result is normalized based on
D0
O STol
RRV = 1
Rt
Dt
AcO AcO
t = 0h t = 2h
Larger the number, higher the reactivity
Zhang, Z.; Ollmann, I. R.; Ye, X.-S.; Wischnat, R.; Baasov, T.; Wong, C.-H. J. Am. Chem. Soc. 1999, 121, 734.
Sequential One-Pot Synthesis of Globo H
OH
OH
OHOH O
HO
O
OHOH O
O
O O
AcNH
HO O OH
O OH HO
HO
OH
O HO Globo H
Globo H 1% overall yield in 19 steps (Denishefsky, 1995)
HO
O HO
O OR HO
Human breast tumor associated antigen. First total synthesis was reported by Danishefsky in 1995 using glycal assembly.
Bilodeau, M. T.; Park, T. K.; Hu, S.; Randolph, J. T.; Danishefsky, S. J.; Livingston, P. O.; Zhang, S. J. Am. Chem. Soc. 1995, 117, 7840.
Sequential One-Pot Synthesis of Globo H OH
OH
OHOH O
HO
OHOH O
O
O
O O
AcNH
OptiMer
HO O OH
O
O
OH HO
OH
HO
Globo H Globo H
HO
O
O HO
HO
OR HO
BnO OBn
Bn =
BzO OBz O
BnO
ClBn = Cl
NO2
R=
O TrocHN
STol OClBn
(67% yield)
OHOBn O
O N H
O
RRV = 6
NBz =
TrocHN =
O O
HO O
NBzO ONBz
O
CCl3
OMe
BnO
STol OBn
OBn
RRV = 72,000
OBn
O BnO BnO
O BnO
O OR BnO
Burkhart, F.; Zhang, Z.; Wacowich-Sgarbi, S.; Wong, C.-H. Angew. Chem. Int. Ed. 2001, 40, 1274.
Sequential One-Pot Synthesis of Globo H O
O BnO
NBzO ONBz O O
BnO
RRV = 6
BnO
R=
BnO
NBz = TrocHN =
N H
Cl OH
OHOH O
HO
O
HO
HO
O O
O
BnO O
OBn
TrocNH
ClBnO O OBn
O
BnO
O
O BnO
OR BnO
1. Zn-AcOH 2. Ac2O-pyridine 3. NaOMe-MeOH 4. H2-Pd/C
O HO O OH
OH
O
Globo H Globo H 20% overall yield
BnO Globo H
O
AcNH
OBn
O
CCl3
OHOH O
41% yield
O
OBn
NO2
O OH
O
BzO ONBz
O O
ClBn =
BzO OBz O
OMe O
Bn =
OR BnO
BzO OBn
O
O
O BnO
STol OClBn
TrocHN
I N
OBn
O
O
O HO
OH
OHOBn
NIS, TfOH, CH2Cl2 BzO OBz
NIS = O
RRV = 72,000
OBn
BnO
BnO OBn
STol OBn
HO HO
O HO
O OR HO
Burkhart, F.; Zhang, Z.; Wacowich-Sgarbi, S.; Wong, C.-H. Angew. Chem. Int. Ed. 2001, 40, 1274.
Other Oligosaccharides Synthesized with OptiMer OH
HO AcHN
OH
HO2C
OH
O
OH
O
O HO
O
O
HO
HO
OH
O NHAc
OH
O O
O
OH
OH
O HO
O OH
OR
OH HO
O
O O
O OH
O AcNH
O OH HO
HO
Sialyl Lewisx hexasaccharide 8% overall yield in 2 one-pot reactions (cf. 4% overall yield in 8 steps)
HO OH
HO OH HO
HO
OH
O O HO
HO2C
O HO
O OR HO
O HO HO
And more..
OH HO NHAc
Fucosyl GM1 6% overall yield in 3 one-pot reaction (cf. 5% overall yield in 15 steps)
Zhang, Z.; Kikura, K.; Huang, X.-F.; Wong, C.-H. Can. J. Chem. 2002, 80, 1051. Mong, T. K.-K.; Lee, H.-K.; Duron, S. G.; Wong, C.-H. Proc. Natl. Acad. Sci. USA 2003, 100, 797.
Comparison of the Two Approaches
Common Advantages: They both reduce labor cost. They both allow for high throughput synthesis of oligosaccharides
Advantages for the one-pot approach over the automated synthesizer: It fundamentally helps planning of oligosaccharide synthesis It involves no intermediate deprotection Scale-up is possible
Heparin-Like Oligosaccharides: A Synthetic Challenge a
OSO3 O HO
O O3SHN O HO
CO2
O O OH O3SO
a
OSO3 O O3SHN O HO
O O2C
O OSO3 HO
OSO3 O O O3SHN
iduronic acid
Belongs to the family of glycosaminoglycans (GAG). Heparin is widely used as an anticoagulant.
Jacquinet, J.-C.; Petitou, M.; Duchaussoy, P.; Lederman, I.; Choay, J.; Torri, G.; Sinay, P. Carbohydr. Res. 1984, 130, 221. Yu, H. N.; Furukawa, J.-I; Ikeda, T.; Wong, C.-H. Org. Lett. 2004, 6, 723. Orgueira, H. A.; Bartolozzi, A.; Schell, P.; Litjens, R. E. J. N.; Palmacci, E. R.; Seeberger, P. H. Chem. Eur. J. 2003, 9, 140.
Outline
1.
Introduction
2.
Solid Phase Approach: Automated Oligosaccharide Synthesizer
3.
Solution Phase Approach: OptiMer One-Pot Oligosaccharide Synthesis
4.
Summary
Summary
1.
Novel strategies towards oligosaccharide synthesis were discussed: - Solid Phase Automated Oligosaccharide Synthesizer - Solution Phase OptiMer One-Pot Oligosaccharide Synthesis
2.
From a chemical point of view, the reactivity based one-pot strategy makes the design of oligosaccharide synthesis easier.
Acknowledgement Prof. John Frost Dr. Karen Frost
Prof. Chris Chang Prof. Babak Borhan Prof. Joan Broderick
Frost Group
The End
Example in Calculating RRV
OAc AcO 1:
AcO AcO
O STol
LevO OH O STol
PMBO
O
40: O BnO
OBn
OBn
Zhang, Z.; Ollmann, I. R.; Ye, X.-S.; Wischnat, R.; Baasov, T.; Wong, C.-H. J. Am. Chem. Soc. 1999, 121, 734.
Accuracy Measurement of Calculated RRV
Experimental values are shown without parentheses Calculated values are shown in parentheses
Zhang, Z.; Ollmann, I. R.; Ye, X.-S.; Wischnat, R.; Baasov, T.; Wong, C.-H. J. Am. Chem. Soc. 1999, 121, 734.
Relationship Between Relative Rates and Substrate Comsumption
Zhang, Z.; Ollmann, I. R.; Ye, X.-S.; Wischnat, R.; Baasov, T.; Wong, C.-H. J. Am. Chem. Soc. 1999, 121, 734.
