OPTICALLY ACTIVE CLELAND'S REAGENT;(R,R)-(-)-1,4-DITHIO-L-THREITOL;1,4-dimercapto-,(r-(r*,r*))-3-butanediol;4-dimercapto-3-butanediol-threo-1;(2R,3R)-THREO-1,4-DIMERCAPTO-2,3-BUTANEDIOL;(2R,3R)-(-)-2,3-DIHYDROXY-1,4-BUTANEDITHIOL;(2R,3R)-(-)-1,4-DIMERCAPTO-2,3-BUTANEDIOL;(-)-1,4-DITHIO-L-THREITOL