Phosphinylalkanoyl substituted prolines

A compound having the formula ##STR27## or a salt thereof, wherein R.sub.1 is alkyl, aryl, arylalkyl, cycloalkyl, or cycloalkylalkyl;

• one of R.sub.2 and R.sub.4 is ##STR28## and the other is hydrogen, alkyl, arylalkyl or ##STR29## wherein X is hydrogen, alkyl or phenyl and Y is hydrogen, alkyl, phenyl or alkoxy, or together X and Y are --(CH.sub.2).sub.2 --, --(CH.sub.2).sub.3 --, --CH.dbd.CH-- or ##STR30## R.sub.3 is hydrogen or alkyl;
• --R.sub.5 --COOR.sub.4 is ##STR31## R.sub.6 is hydrogen, hydroxy, alkyl, halogen, azido, amino, cycloalkyl, aryl, arylalkyl, carbamoyloxy, N,N-dialkylcarbamoyloxy, or --Z--R.sub.9 ;
• R.sub.7 and R.sub.7 ' are the same and each is halogen or --Z--R.sub.10, or R.sub.7 and R.sub.7 ' together are .dbd.O, --O--(CH.sub.2).sub.m --O-- or --S--(CH.sub.2).sub.m --S--;
• R.sub.8 is hydrogen and R.sub.8 ' is phenyl, 2-hydroxyphenyl or 4-hydroxyphenyl or R.sub.8 and R.sub.8 ' together are .dbd.O;
• R.sub.9 is alkyl, aryl, arylalkyl, 1- or 2-naphthyl, or biphenyl;
• R.sub.10 is alkyl, aryl or arylalkyl;
• Z is oxygen or sulfur;
• n is 0 or 1;
• and
• m is 1 or 2;
• and wherein the term "aryl" refers to phenyl or phenyl substituted with halogen, alkyl, alkoxy, alkylthio, hydroxy, alkanoyl, nitro, amino, dialkylamino or trifluoromethyl groups;
• the term "alkyl" refers to groups having 1 to 10 carbon atoms;
• the term "alkoxy" refers to groups having 1 to 8 carbon atoms;
• the term "cycloalkyl" refers to groups having 3 to 7 carbon atoms;
• and the term "alkanoyl" refers to groups having 2 to 9 carbon atoms.