Preparation and use of mercaptoacylproline derivative

NEW MATERIAL: A compound of formula I [wherein X-R 1 is in position 3 or 4 of a proline ring; X is O or S; R is H or an alkyl; R 1 is an alkyl, an alkenyl, an alkynyl, (substituted) phenyl or (substituted) phenylalkylene; R 2 and R 3 are each H, an alkyl or CF 3 ; R 4 ' is formula II (wherein R 5 is an alkyl, phenyl or a phenylalkylene); and n is 0-2] or a salt thereof. EXAMPLE: I-(3-Mercapto-1oxopropyl)-trans-methoxyL-proline sodium salt. USE: An antihypertensive useful especially as a remedy against angiotensin-related hypertension. PREPARATION: A proline compound of formula III is reacted with an acid of formula IV or a reactive derivative thereof to obtain a compound of formula I. COPYRIGHT: (C)1989,JPO