Compounds of the structure ##STR1## wherein: Q is oxygen, sulfur or imino.X and Y are hydrogen, halogen, hydroxy, alkoxy, trifluoromethyl, nitro, carboxy, cyano, sulfonamido, sulfhydryl, alkyl, alkenyl, alkynyl, alkanoyl, alkylmercapto, amino, alkylamino, dialkylamino, alkysulfinyl, and alkylsulfonyl and may be the same or different;R.sub.1 is hydrogen, alkanoyl, substituted alkanoyl wherein the substituent is hydroxy, amino or cycloalkyl, aroyl, arylalkanoyl, or cycloalkylcarbonyl,n is an integer from 1 to 4 inclusive,R.sub.2 and R.sub.3 are hydrogen, alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkyl-alkyl, aryl, aralkyl, and substituted derivatives thereof wherein the substituents are hydroxy, amino, alkylamino, dialkylamino, alkoxy, halogen, hydroxy, mercapto, alkylmercapto and nitro, and may be the same or different;M is alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkylalkyl, aryl, aralkyl, and hetero; andZ is hydroxy, amino, alkylamino, dialkylamino, or alkoxy,have angiotensin converting enzyme inhibitory activity.