ASYMMETRIC SYNTHESIS OF β-SUBSTITUTED δ-KETOESTERS VIA MICHAEL-ADDITIONS OF SAMP/RAMP-HYDRAZONES TO α,β-UNSATURATED ESTERS, VIRTUALLY COMPLETE 1.6-ASYMMETRIC INDUCTION

Article abstract of DOI:10.1016/S0040-4039(01)99823-5

A simple and efficient 3-step asymmetric synthesis of β-substituted δ-ketoesters 3 in 45-62percent overall chemical yield and >=96-ca.100percent ee is described.The key step is an asymmetric Michael-addition of lithiated methylketone-SAMP- or RAMP-hydrazones to α,β-unsaturated esters 2 with virtually complete 1.6-asymmetric induction.