Heterocyclic oxophthalazinyl acetic acids

DETAILED DESCRIPTION OF THE INVENTION The numbering system of the compounds of formula I is as shown: ##STR5## The term "(C.
sub.
1 -C.
sub.
4)alkyl" whenever used in the definitions of R.
sub.
1 to R.
sub.
4 denotes saturated monovalent straight or branched aliphatic hydrocarbon radicals having one to four carbon atoms, such as methyl, ethyl, propyl, butyl, t-butyl etc.
The term "prodrug" denotes a group that is converted in vivo into the active compound of formula I wherein R.
sub.
1 is hydroxy.
Such groups are generally known in the art and include ester forming groups, to form an ester prodrug, such as benzyloxy, di(C.
sub.
1 -C.
sub.
4)alkylaminoethyloxy, acetoxymethyl, pivaloyloxymethyl, phthalidoyl, ethoxycarbonyloxyethyl, 5-methyl-2-oxo-1,3-dioxol-4-yl methyl, and (C.
sub.
1 -C.
sub.
4)alkoxy optionally substituted by N-morpholino and amide-forming groups such as di(C.
sub.
1 -C.
sub.
4)alkylamino.
The heterocyclic 5-membered ring having one to three nitrogenatoms, one of which may be replaced by oxygen or sulfur includes imidazolyl, oxazolyl, thiazolyl, pyrazolyl, oxadiazolyl, thiadiazolyl, and triazolyl.
The heterocyclic 6-membered ring having one to three nitrogen atoms, or one or two nitrogen atoms and one oxygen or sulfur includes triazinyl, pyrimidyl, pyridazinyl, oxazinyl and triazinyl.
The heterocyclic ring may be condensed with benzo so that said ring is attached at two neighboring carbon atoms to form a phenyl group.
Such benzoheterocyclic ring may be attached to Z either through the heterocyclic group or through the benzo group of the benzoheterocyclic ring.
The preparation of those compounds wherein Z is attached to the benzo group is illustrated in Reaction Scheme B below.
Specific examples wherein said heterocyclic ring is condensed with a benzo include benzoxazolyl, quinazolin-2-yl, 2-benzimidazolyl, quinazolin-4-yl and benzothiazolyl.
The oxazole or thiazole condensed with a 6-membered aromatic group containing one or two nitrogen atoms include positional isomers such as oxazolo[4,5-b]pyridine-2-yl, thiazolo[4,5-b]pyridine-2-yl, oxazolo[4,5-c]pyridine-2-yl, thiazolo[4,5-c]pyridine-2-yl, oxazolo[5,4-b]pyridine-2-yl, thiazolo[5,4-b]pyridine-2-yl, oxazolo[5,4-c]pyridine-2-yl, and thiazolo[5,4-c]pyridine-2-yl