Enantio- and diastereoselective cyclopropanation with tert-butyl α-diazopropionate catalyzed by dirhodium(II) tetrakis[N-tetrabromophthaloyl-(S)-tert-leucinate]
The first successful example of a catalytic asymmetriccyclopropanation with α-diazopropionates is described. The cyclopropanation reaction of 1-aryl-substituted and related conjugated alkenes with tert-butyl α-diazopropionate has been achieved by catalysis with dirhodium(II) tetrakis[N-tetrabromophthaloyl-(S)-tert-leucinate], Rh2(S-TBPTTL)4, providing the corresponding cyclopropane products containing