The enantioselective preparation of key intermediates in the synthesis of transition state analogues of hypoxanthine-guanine phosphoribosyltransferase,(1S, 2S, 3R, 4R)-4- acetoxymethyl-1-bromomethyl-2, 3-isopropylidenedioxy-1-toluenesulfonamidocyclopentane (3a) and the 4-nitrobenzenesulfonamido analogue (3b), are described.