Dipeptide isosteres. 2. Synthesis of hydroxyethylene dipeptide isostere diastereomers from a common γ-lactone intermediate. Preparation of renin and HIV-1 protease inhibitor transition state mimics.

Abstract A general strategy for the synthesis of the hydroxyethylene dipeptide isostere diastereomers C or D has been developed. The syntheses proceeded through a common γ-lactone intermediate A or B . The C(3α) γ-lactone diastereomer A was prepared from the N-Cbz protected α-amino aldehyde and 2-(2-isopropylpropen-2-yl)trimethylsilane in five steps. The C(3β) γ-lactone diastereomer B was obtained by kinetic protonation of the lactone enolate using malonate derivatives.