Syn-allylstannation of N-acyliminium intermediates by tributyl[γ- (silyloxy)allyl]stannanes: A key reaction for the diastereoselective synthesis of polyhydroxypiperidines and polyhydroxyazepanes

摘要

The allylstannation of N-alkenyl N-acyliminium intermediates by tributyl[γ-(silyloxy)allyl]stannanes afforded the expected adducts with a high syn-selectivity (up to 99:1). Ensuing ring-closing metathesis afforded dehydropiperidines or dehydroazepanes which were engaged in a stereoselective dihydroxylation reaction leading to polyhydroxypiperidines or polyhydroxyazepanes in good yields. This sequence was applied to a diastereoselective synthesis of (±)-1-deoxy-gulonojirimycine.