Lewis acid catalyzed diastereoselective [3+4]-annulation of donor-acceptor cyclopropanes with anthranils: synthesis of tetrahydro-1-benzazepine derivatives.

A Lewis acid catalyzed [3+4]-annulation reaction between cyclopropane 1,1-diesters and anthranils has been developed. This annulation consists of a reaction sequence involving ring-opening/aromatization/nucleophilic addition. Thereinto, aromatization is the driving force for this annulation. Using this reaction, a series of 8-oxa-1-azabicyclo[3.2.1]octanes can be prepared conveniently with excellent diastereoselectivity.