STEREOCONTROLLED PREPARATION OF C-2-DEOXY-α- AND -β-D-GLUCOPYRANOSYL COMPOUNDS FROM TRIBUTYL-(2-DEOXY-α- AND -β-D-GLUCOPYRANOSYL)STANNANES

Article abstract of DOI:10.1016/S0008-6215(00)90893-0

Tributylstannyllithium treatment of 3,4,6-tri-O-benzyl-2-deoxy-α-D-arabino-hexopyranosyl chloride (2) provided selectively tributyl (3,4,6-tri-O-benzyl-2-deoxy-β-D-arabino-hexopyranosyl)stannane (3) in 85percent yield.Isomeric tributyl (3,4,6-tri-O-benzyl-2-deoxy-α-D-arabino-hexopyranosyl)stannane (6) could be prepared in 70percent yield by reductive lithiation of 2 and reaction with tributyltin chloride.Tin-lithium exchange reaction, performed on 3 and 6 with butyllithium in oxolane at -78 deg C, generated the corresponding, configurationally stable 2-deoxy-β- and -α-D-hexopyranosyllithium compounds which reacted with electrophilic compounds with retention of configuration.Addition of these glycosyllithium reagnts to prochiral carbonyl compounds gave variable degrees of facial selectivity.A significant diastereofacial discrimination (10:1) was observed by condensation of 3,4,6-tri-O-benzyl-2-deoxy-α-D-arabino-hexopyranosyllithium reagent with hexanal and isobutyraldehyde.The structure of all C-glycopyranosyl compounds obtained was established by 1H-n.m.r. spectroscopy.