Novel Synthesis of Three Types of C-Terminal Components of Renin Inhibitors from Unnatural(2S, 3S)-Tartaric Acid

The addition reaction of cyclohexylmethylmagnesium bromide with the imine prepared from unnatural(2S, 3S)-tartaric acid was found to proceed in a highly stereoselective manner in the presence of cerium(III) chloride. A chelation-controlled mechanism could explain the stereochemical outcome of the addition reaction. The addition product could be elaborated into three types of C-terminal components of renin inhibitors by employing oxidative cleavage of the 1, 2-diol moiety, epoxide formation with inversion of configuration, and epoxide opening with a nucleophile.