sulfonyl or r 5 and r 6 together form a ring application_number US 55247700 A description the novel compounds encompassed by the instant invention can be described by the general formula i set forth above or the pharmaceutically acceptable non toxic salts thereof in addition the present invention also encompasses compounds of formula ii wherein n m a d x y r 4 r 5 r 6 and r 8 are as defined above for formula i preferred compounds of formula ii are where n is 1 m is 0 a is co 2 r 9 d is nr 1 r 12 r 4 is o x is n y is u2014 s aryl u2014 o aryl or u2014 ch 2 aryl r 9 is hydrogen or lower alkyl r 8 is hydrogen or lower alkyl r 12 is hydrogen and r 1 is a substituted or unsubstituted aryl or arylalkyl by u201c alkyl u201d u201c lower alkyl u201d and u201c c 1 c 6 alkyl u201d in the present invention is meant straight or branched chain alkyl groups having 1 6 carbon atoms such as methyl ethyl propyl isopropyl n butyl sec butyl tert butyl pentyl 2 pentyl isopentyl neopentyl hexyl 2 hexyl 3 hexyl and 3 methylpentyl these groups may be substituted with up to four groups mentioned below for substituted aryl by u201c alkoxy u201d u201c lower alkoxy u201d and u201c c 1 c 6 alkoxy u201d in the present invention is meant straight or branched chain alkoxy groups having 1 6 carbon atoms.