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DOI: 10.1055/s-1990-21142
A Short Homochiral Synthesis of Substituted Pyrrolidines
Publication History
Publication Date:
08 March 2002 (online)
A simple and efficient highly stereocontrolled route to trisubstituted vinylpyrrolidines like (3S,4S)-1-benzyl-3,4-di-benzyloxy-2-vinylpyrrolidine (5) from monosaccharides is reported. The procedure, illustrated in the D-gluco series, involves treating methyl 6-bromohexopyranosides like methyl 4-O-benzoyl-2,3-di-O-benzyl-6-bromo-α-D-glycopyranoside (2) with zinc, sodium cyanoborohydride and benzylamine in propanol/water at reflux. Under these conditions, reductive ring opening of the bromosugar to an ω-alkenylaldehyde is followed by in situ reductive amination of the carbonyl with benzylamine and spontaneous intramolecular displacement of a C4-benzoate ester, now made allylic by the newly-formed alkene.