Synthesis of 7-azabicyclo[2.2.1]heptanes by anionic cyclization

Abstract

Cyclizations of α-amino-organolithiums, derived by tin-lithium exchange, which proceed via a stereoselective two-electron process and totally regiospecific 5- exo-trig ring closure, have been extended to the preparation of the 7-azabicyclo[2.2.1]heptane ring system. Cyclization occurs from either the cis or the trans isomer of 5-allyl-2-tri- n-butylstannyl- N-benzylpyrrolidine to give only the exo product as a single diastereomer in isolated yields up to 83%.