(Salen)Ti(IV)-Catalyzed Asymmetric Ring-Opening of Monosubstituted Epoxides with Dithiophosphorus Acid

The asymmetric ring-opening of monosubstituted epoxides with dithiophosphorus acids catalyzed by a (salen)Ti(IV) complex formed in situ from the reaction of Ti(OPr-i)4 and the chiral salen ligand derived from (1R,2R)-(+)-diaminocyclohexane and (R)-2,2'-diamino-1,1'- binaphthalene was realized. The resulting products were obtained with moderate enantioselectivity (up to 57% ee). High regioselectivity was observed for the alkyl substituted epoxides, whereas poor regioselectivity was obtained for the aryl substituted epoxides.