Phosphonyl hydroxyacyl amino acid derivatives as antihypertensives

A compound of the formula ##STR428## and pharmaceutically acceptable salts thereof wherein:

• X is ##STR429## R.sub.9, R'.sub.9, R.sub.10 and R'.sub.10 are independently selected from hydrogen and lower alkyl or R'.sub.9, R.sub.10, R'.sub.10 are hydrogen and R.sub.9 is ##STR430## R.sub.11 is hydrogen, lower alkyl of 1 to 4 carbons, lower alkoxy of 1 to 4 carbons, lower alkylthio of 1 to 4 carbons, chloro, bromo, fluoro, trifluoromethyl, hydroxy, phenyl, phenoxy, phenylthio, or phenylmethyl;
• R.sub.12 is hydrogen, lower alkyl of 1 to 4 carbons, lower alkoxy of 1 to 4 carbons, lower alkylthio of 1 to 4 carbons, chloro, bromo, fluoro, trifluoromethyl, or hydroxy;
• m is zero, one, two or three;
• p is one, two or three provided that p is more than one only if R.sub.11 or R.sub.12 is hydrogen, methyl, methoxy, chloro, or fluoro;
• R.sub.21 is hydrogen, lower alkyl, cycloalkyl, phenyl or ##STR431## R.sub.22 is hydrogen, lower alkyl, ##STR432## r is an integer from 1 to 4;
• R.sub.1 is alkyl of 1 to 10 carbons, aminoalkyl, haloalkyl, ##STR433## wherein q is zero or an integer from 1 to 7;
• and R.sub.11 and p are as defined above;
• and
• R.sub.19 and R.sub.20 are independently selected from the group consisting of hydrogen, lower alkyl, halo substituted lower alkyl, ##STR434## wherein m, R.sub.11 and p are as defined above;
• R.sub.2 is hydrogen, lower alkyl, halo substituted lower alkyl, ##STR435## wherein r is as defined hereinbefore;
• R.sub.3 and R.sub.6 are independently selected from hydrogen, lower alkyl, benzyl, benzhydryl, alkali metal or ##STR436## wherein R.sub.15 is hydrogen, lower alkyl, cycloalkyl, or phenyl, and R.sub.16 is hydrogen, lower alkyl, lower alkoxy, phenyl, or R.sub.15 and R.sub.16 taken together are --(CH.sub.2).sub.2 --, --(CH.sub.2).sub.3, --CH.dbd.CH-- or ##STR437##