Intermolecular C-H functionalization versus cyclopropanation of electron rich 1,1-disubstituted and trisubstituted alkenes

摘要

Rhodium(II)-catalyzed reactions of aryldiazoacetates with election rich 1,1-disubstituted and trisubstituted alkenes Were systematically studied. The regio-, diastereo- and enantioselectivity of the chemistry was profoundly influenced by the nature of the Substrates and the catalyst. Conditions were developed for either selective cyclopropanation or C-H insertion. Both reactions can be achieved with high diastereo- and enantioselectivity (for C-H insertion: >90% de, Lip to 96% ee, for cyclopropanation. > 94% de, up to 95% ee), For the 1,1-disubstituted vinyl Others, cyclopropanation occurs with variable diastereoselectivity but in optimized systems (lie cyclopropane is formed in >94% de and up to 98% ee.