The new 6-deoxy-D-allal- and 6-deoxy-D-galactal-derived allyl epoxides 8α and 8β have been stereoselectively prepared and their behaviour as glycosyl donors in addition reactions with nucleophiles examined and compared with that of the corresponding 6-OR (R= Bn, Tr) substituted epoxides. The completely stereoselective substrate-dependent glycosylation process found in the reaction of 8α and 8β with O-nucleophiles (alcohols and partially protected monosaccharides) and C-nucleophiles (alkyl lithium compounds and TMSCN), indicated that a 6-OR group in the side chain is not necessary for determining the selectivity. The reaction of 8α and 8β with azide (TMSN3, N-nucleophile) made it possible to revise a previously proposed rationalization for the formation of the corresponding cis azido alcohol (syn-1,2-addition product).
|Autori:||DI BUSSOLO V; FAVERO L; ROMANO M.R; PINESCHI M; CROTTI P|
|Titolo:||Synthesis of diastereoisomeric 6-deoxy-D-allal- and 6-deoxy-D-galactal-derived allyl epoxides and examination of the regio- and stereoselectivity in nucleophilic addition reaction. Comparison with the corresponding 6-O-functionalized allyl epoxides|
|Anno del prodotto:||2008|
|Digital Object Identifier (DOI):||10.1016/j.tet.2007.06.039|
|Appare nelle tipologie:||1.1 Articolo in rivista|