carbons oh sh alkoxy of 1 to 6 carbons or alkylthio of 1 to 6 carbons and r 3 is hydrogen lower alkyl of 1 to 6 carbons or f and z is u2014 c u2261 c u2014 u2014 n u2550 n u2014 u2014 n u2550 cr 1 u2014 u2014 cr 1 u2550 n u2014 cr 1 u2550 cr 1 n u2032 u2014 where n u2032 is an integer having the value 0 5 u2014 co u2014 nr 1 u2014 u2014 cs u2014 nr 1 u2014 u2014 nr 1 u2014 co u2014 nr 1 u2014 cs u2014 coo u2014 u2014 oco u2014 u2014 cso u2014 u2014 ocs u2014 y is a phenyl or naphthyl group or heteroaryl selected from a group consisting of pyridyl thienyl furyl pyridazinyl pyrimidinyl pyrazinyl thiazolyl oxazolyl imidazolyl and pyrrazolyl said phenyl and heteroaryl groups being optionally substituted with one or two r 2 groups or when z is u2014 cr 1 u2550 cr 1 n u2032 u2014 and n u2032 is 3 4 or 5 then y represents a direct valence bond between said cr 2 u2550 cr 2 n u2032 group and b a is ch 2 q where q is 0 5 lower branched chain alkyl having 3 6 carbons cycloalkyl having 3 6 carbons alkenyl having 2 6 carbons and 1 or 2 double bonds alkynyl having 2 6 carbons and 1 or 2 triple bonds b is hydrogen cooh or a pharmaceutically.