Phosphonamidate compounds

Claim 1

A compound of the formula ##STR154## and pharmaceutically acceptable salts thereof wherein: X is ##STR155## R 4 is hydrogen, lower alkyl, --(CH 2 ) m -cycloalkyl, or ##STR156## R 5 is hydrogen, lower alkyl, ##STR157## R 1 is hydrogen, lower alkyl, or cycloalkyl; R 2 is hydrogen, lower alkyl, halo substituted lower alkyl, ##STR158## R 21 is alkyl of 1 to 10 carbons, ##STR159## R 13 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 14 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; r is an integer from one to four; m is zero, one, two or three; p is one, two or three provided that p is more than one only if R 13 or R 14 is hydrogen, methyl, methoxy, chloro, or fluoro; q is zero or an integer from one to seven; s is an integer from one to eight; R 3 and R 6 are independently selected from the group consisting of hydrogen, lower alkyl, benzyl, benzhydryl, and ##STR160## R 17 is hydrogen, lower alkyl, cycloalkyl, or phenyl; and R 18 is hydrogen, lower alkyl, lower alkoxy, phenyl, or R 17 and R 18 taken together are --(CH 2 ) 2 --, (CH 2 ) 3 , --CH═CH--, or ##STR161##