Abstract:
There are disclosed certain 2H-pyrido[4,3-b][1,4]oxazines and 2H-pyrido[4,3-b][1,4]thiazines which possess biological activity. The compounds have the structure: ##STR1## wherein n has a value of 1,2 or 3; X is oxygen or sulfur; R. sub. 1 is a lower alkyl group, e. g. , an alkyl group containing up to six carbon atoms such as methyl, ethyl, propyl, butyl, etc. ; R. sub. 2 is a member selected from the group consisting of hydrogen, alkyl radicals having from about one to about 12 carbon atoms, preferably from about one to about six carbon atoms; alkenyl radicals having from about two to about 15 carbon atoms; preferably from about two to about 10 carbon atoms; cycloalkyl radicals having from about three to about 20 carbon atoms, preferably from about three to about 15 carbon atoms; aryl, aralkyl and alkaryl radicals having from about six to about 20 carbon atoms, preferably from about six to about 15 carbon atoms; a halogen radical, e. g. , chlorine, fluorine, bromine and iodine; a hydroxyl group; an amino group; an alkoxy or aryloxy group; a carboxyl group or an alkylcarboxyl group having from about one to about 10 carbon atoms, preferably from about one to about five carbon atoms; an alkythio group or an arylthio group having from about one to about 20 carbon atoms, preferably from about one to about 15 carbon atoms; a sulfonic acid group or alkyl- or arylsulfonyl group having from about one to about 20 carbon atoms, preferably from about one to about 15 carbon atoms; an alkyl- or arylsulfinyl group having from about one to about 20 carbon atoms, preferably from about one to about 15 carbon atoms; an alkyl- or aryl mono- or diamino group having from about one to about 20 carbon atoms, preferably from about one to about 15 carbon atoms; a hydrocarbyl group, such as defined above, carrying halogen, hydroxyl, amino, alkoxy or aryloxy; when taken together with the aromatic ring to which it is attached, a fused ring structure such as naphthyl; and, when taken together with R. sub. 3, an alkylene radical containing from about one to about 12 carbon atoms, preferably from about one to about six carbon atoms; R. sub.