A convenient synthesis of optically pure (2R, 3R)-2, 3-epoxysuccinyl - Dipeptides

Article abstract of DOI:10.1016/S0040-4020(01)85561-7

(2R,3R)-trans-Epoxysuccinyl-dipeptides (7a-7d) were synthesized by acylation of dipeptides with the N-hydroxysuccinimide or pentafluorophenyl ester of monoethyl (2R,3R)-trans-epoxysuccinate (6a-6b). A nucleophilic oxirane ring opening by N-hydroxysuccinimide and pentafluorophenol during the preparation of the active esters could not be observed. Subsequent saponification of the monoethyl ester 7a-7d with KOH in ethanolic solution allowed to produce the dipeptide derivatives as potassium salts (8a-8d) which were found to be stable on storage in the cold. The attempts to convert (2R,3R)-trans-epoxysuccinyl-glycyl-proline (7a) into the corresponding (2S,3S)-trans-epithiosuccinyl derivative via an oxygen sulfur exchange reaction with 3-methylbenzothiazole-2-thione failed completely as among the various products of unknown nature formed only the desulfurated fumaryl derivative could be isolated and characterized.