Diastereoselective Cyclopropanation through Michael Addition‐Initiated Ring Closure between α,α‐Dibromoketones and α,β‐Unsaturated Fischer Carbene Complexes

Abstract

The diastereoselective synthesis of tetrasubstituted cyclopropanes is described. The two-step procedure is based on the 3-exo-tet Michael addition-initiated ring closure. In the first step, the enolates derived from α,α-dibromoketones react with the α, -unsaturated Fischer alkoxycarbene complexes to [a] 431 Scheme 3. Conversion of cyclopropane 4 to ester 5.[a] The MIRC and demetallation was performed in a one-pot setup.[b] The cyclopropane 5aa was prepared from the tungsten carbene complex 4m.