Stereocontrolled synthesis of the D- and L-glycero-beta-D-manno-heptopyranosides and their 6-deoxy analogues. Synthesis of methyl alpha-l-rhamno-pyranosyl-(1-->3)-D-glycero-beta-D-manno-heptopyranosyl- (1-->3)-6-deoxy-glycero-beta-D-manno-heptopyranosyl-(1-->4)-alpha-L- rhamno-pyranoside, a tetrasaccharide subunit of the lipopolysaccharide from Plesimonas shigelloides.
The synthesis of d- and l-glycero-alpha-manno-thioheptopyranosides, protected with 4,6-O-alkylidene-type acetals is described. In glycosylations carried out with preactivation with the 1-benzenesulfinylpiperidine/trifluoromethanesulfonic anhydride couple, both the D- and L-glycero series exhibit excellent beta-selectivity with a range of glycosyl acceptors. In contrast, a 4,7-O-alkylidene acetal was found not to afford beta-selectivity. With a 4,6-O-[1-cyano-2-(2-iodophenyl)ethylidene] acetal protected thioglycoside, excellent beta-selectivity was obtained in glycosylation reactions, and subsequent treatment with tributyltin hydride and azoisobutyronitrile brought about clean fragmentation to the 6-deoxy-glycero-beta-D-manno-heptopyranosides. This chemistry was applied to the stereocontrolled synthesis of methyl alpha-L-rhamno-pyranosyl-(1-->3)-D-glycero-beta-D-manno-heptopyranosyl-(1-->3)-6-deoxy-glycero-beta-D-manno-heptopyranosyl-(1-->4)-alpha-L-rhamno-pyranoside, a component of the lipopolysaccharide from Plesimonas shigelloides.
Crich
David
D
Department of Chemistry, University of Illinois at Chicago, 845 West Taylor Street, Chicago, Illinois 60607-7061, USA. dcrich@uic.edu
Banerjee
Abhisek
A
D000080:Acetals / Q000737:chemistry; D000475:Alkenes / Q000737:chemistry; D001391:Azo Compounds / Q000737:chemistry; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D003837:Deoxy Sugars / Q000138:chemical synthesis*; D006031:Glycosylation; D006539:Heptoses / Q000138:chemical synthesis*; D008070:Lipopolysaccharides / Q000737:chemistry*; D008698:Mesylates / Q000737:chemistry; D008759:Methylglycosides / Q000138:chemical synthesis*; D008956:Models, Chemical; D008969:Molecular Sequence Data; D009570:Nitriles / Q000737:chemistry; D009844:Oligosaccharides / Q000138:chemical synthesis*; D010880:Piperidines / Q000737:chemistry; D016981:Plesiomonas / Q000737:chemistry*; D012210:Rhamnose / Q000031:analogs & derivatives / Q000138:chemical synthesis*; D013237:Stereoisomerism; D013441:Sulfinic Acids / Q000737:chemistry; D014220:Trialkyltin Compounds / Q000737:chemistry
D000080:Acetals; D000475:Alkenes; D001391:Azo Compounds; D003837:Deoxy Sugars; D006539:Heptoses; D008070:Lipopolysaccharides; D008698:Mesylates; D008759:Methylglycosides; D009570:Nitriles; D009844:Oligosaccharides; D010880:Piperidines; D013441:Sulfinic Acids; D014220:Trialkyltin Compounds; C026312:glycero-manno-heptose; C011559:tributyltin; C425152:benzenesulfinic acid; C032727:piperidine; C012077:trifluoromethanesulfonic acid; D012210:Rhamnose