Fused pyrimidine systems: XIV. Reaction of 2-alkenyl(alkynyl)sulfanylpyrido[3,4-d]pyrimidin-4(3H)-ones with arylsulfanyl chlorides

2-Allylsulfanylpyrido[3,4- d ]pyrimidin-4(3 H )-one reacted with arylsulfanyl chlorides in chloroform to give addition products to the exocyclic double bond, which were converted into linearly fused arylsulfanylthiazinopyridopyrimidines by the action of sodium acetate. The reactions of 2-allyl(cinnamyl, propargyl)sulfanylpyrido[3,4- d ]pyrimidin-4(3 H )-ones with arylsulfanyl chlorides in the presence of an equimolar amount of lithium perchlorate afforded angularly fused arylsulfanylmethylthiazolo- and -thiazinopyridopyrimidines.