Diastereoselective Trifluoromethylation of Chiral alpha,beta-Unsaturated N-tert-Butanesulfinyl Ketimines with Ruppert-Prakash Reagent: Asymmetric Synthesis of alpha-Tertiary Trifluoromethyl Allylic Amines

摘要

The diastereoselective trifluoromethylation of chiral alpha,beta-unsaturated N-tert-butanesulfinyl ketimines with Ruppert-Prakash reagent (TMSCF3) has been attained, which provided a convenient and straightforward method for the asymmetric synthesis of structurally diverse alpha-tertiary trifluoro-methyl allylic amines in high yields and with excellent diastereoselectivities (dr up to 99:1). The stereochemical outcome of the present diastereoselective trifluoromethylation of the alpha,beta-unsaturated N-tert-butanesulfinyl ketimines suggested that a cyclic six-membered transition state is involved in the reaction, which is remarkably different from that of the trifluoromethylation of N-tert-butanesulfinyl aldimines.