title: Synthesis of C-septanosides from pyranoses via vinyl addition and electrophilic cyclization.
abstract: A two-step synthesis of C-septanosides from pyranoses is reported. Vinyl addition to tetra-O-benzyl D-glucose, D-galactose, and D-mannose gave the corresponding allylic alcohols. Electrophilic cyclization followed by treatment with iodine gave iodomethyl C-septanosides suitable for substitution reactions. The cyclizations were diastereoselective, giving cis-1,2 configured C-septanosides. Selectivity is rationalized through a model for electrophilic additions that invokes the conformation of the allylic system. This new approach should be generally applicable to the synthesis of a variety of C-septanosides.
authors.affiliation: Department of Chemistry, University of Connecticut, 55 North Eagleville Road, U-3060, Storrs, Connecticut 06269, USA.
authors.forename: Raghu
authors.initials: R
authors.lastname: Vannam
authors.forename: Mark W
authors.initials: MW
authors.lastname: Peczuh
mesh_terms: D000438:Alcohols / Q000737:chemistry; D002384:Catalysis; D003500:Cyclization; D006571:Heterocyclic Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D008358:Mannose; D015394:Molecular Structure; D009005:Monosaccharides / Q000138:chemical synthesis* / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D000438:Alcohols; D006571:Heterocyclic Compounds; D009005:Monosaccharides; D008358:Mannose