Two independent syntheses of (2S,4S)- and (2S,4R)-[5,5-2H2]-5,5′-dihydroxyleucine

Abstract Two independent stereoselective syntheses have been used to prepare samples of (2S,4S)-[5,5- 2 H 2 ]-5,5′-dihydroxyleucine ( 3b ) and the (2S,4R)-diastereoisomer ( 3a ). The first synthesis uses (2S)-pyroglutamic acid as starting material and provides the (2S,4S)-isomer ( 3b ), while the second starts with (2S,4R)-4-hydroxyproline and provides the (2S,4R)-isomer ( 3a ).