Stereo-controlled approach to pyrrolidine iminosugar C-glycosides and 1,4-dideoxy-1,4-imino-L-allitol using a D-mannose-derived cyclic nitrone

摘要

Intramolecular N-alkylation of 2,3-O-isopropylidene-5-O-methanesulfonyl-6-O-t-butyldimethylsilyl-D-mannofuranose-oxime 7 afforded a five-membered cyclic nitrone 9, which on N-O bond reductive cleavage followed by deprotection of -OTBS and acetonide functionalities gave 1,4-dideoxy-1,4-imino-L-allitol (DIA) 3. Addition of allylmagnesium chloride to nitrone 9 afforded α-allylated product 10a in high diaste-reoselectivity providing an easy entry to N-hydroxy-Cl-α-allyl-substituted pyrrolidine iminosugar 4a after removal of protecting group, while N-0 bond reductive cleavage in 10a afforded Cl-ot-allyl-pyrrol-idine iminosugar 4b.