CONFORMATIONAL STUDIES BY H-1 AND C-13 NMR OF LISINOPRIL

Lisinopril, -[(s)-1-carboxy-3-phenylpropyl]-L-lysyl-L-proline) (MK-521 ). is an inhibitor of angiotensin-converting enzyme and a new drug for the treatment of hypertension. H-1 and C-13 NMR studies have shown th at the s-trans to s-cis equilibrium about the amide bond is strongly d ependent on the configuration of the chiral centres. Vicinal coupling constants of stereochemical significance were obtained in deuterated s olvent using NMR techniques. Comparison with values calculated for lis inopril using potential energy calculations and NMR show that lisinopr il exists in preferred optimum conformation in solution.