Preferred Conformations of Captopril and Its Disulfide Metabolite in Deuterium Oxide Deduced from 200 MHz ¹H NMR Spectra

Abstract

The 200 MHz ¹H NMR spectra of Captopril (1) and its mammalian disulfide (2) have been studied. Preferred conformations of these compounds in aqueous solution are discussed. The ratio of the E/Z-isomers is 1:9 at pD 2.3 and 2:3 at pD 7.5, respectively. The populations of various rotamers around the C-6-C-7 bond are estimated. The conformation of the disulfide metabolite is similar to that of captopril.

Key Words:

• ¹H NMR 200 MHz assignments
• Preferred conformations of captopril and mammalian disulfide metabolite
• Rotamers of captopril and its metabolite
• Antihypertensive agents
• Angiotensin converting enzyme inhibitor