The stereoselective preparation of 1,2,3-substituted cyclopropanes from α,β-unsaturated carbonyl compounds in the carboxylic acid oxidation state through Michael addition-initiated ring-closure reactions is a significant challenge in organic synthesis. Herein, the previously elusive catalytic asymmetric cyclopropanation of α,β-unsaturated amides with stabilized sulfur ylides has been efficiently accomplished utilizing a chiral Cu(I) complex. This Lewis acid catalytic system effectively converts a wide range of electron-deficient alkenes into the corresponding 1,2,3-trisubstituted cyclopropanes under mild reaction conditions in good to excellent yields with both high to excellent enantio- and diastereoselectivities. The resulting enantiomerically enriched cyclopropane amides can be readily diversified into promising synthetic intermediates such as β-aminocyclopropanecarboxylic acids with the facile recovery of the 7-azaindoline auxiliary without influencing the optical purity of the cyclopropane unit, which highlights the synthetic efficacy of this catalytic approach.
ASJC Scopus subject areas
- 化学 (全般)