Synthesis of a long acting HIV protease inhibitor via metal or enzymatic reduction of the appropriate chloro ketone and selective zinc enolate condensation with an amino epoxide

This paper describes a new convergent approach to the synthesis of an HIV protease inhibitor which was designed to be suitable in long acting formulations. Unique features in the synthesis include an asymmetric hydrogenation as well as enzymatic reduction of a key chloro ketone intermediate, to set the threo stereochemistry in the corresponding epoxide and the diastereoselective coupling of the latter with the zinc enolate of a suitable functionalized amide derivative.