2-Mercapto-S-phenylazo-4,6-dimethylpyridine-3-carbonitr(i3l)e reacts with halocompounds to give Salkylated
derivatives (421-h) which upon treatment with sod. ethoxide in ethanol, the thienopyridines
(5a-h) was obtained. Compound (5) converted into pyridothienopyrimidines (6a-e) or (7a,b) boiling
with triethyl orthoformate or acetic anhydride. Also it can be converted into pyridothienotriazine (8ad)
by treating with nitrous acid. Chloropyridothienopyrimidine (IOa,b) was obtained by refluxing compound 6a or 7a with POCI3.