A study of the reactions of 2-aryl-4-hydroxy-6H-1,3-thiazin-6-ones with chromone-3-carboxaldehydes

Reaction of 3-formylchromones with 2-aryl-4-hydroxy-6H-1,3-thiazin-6-ones in the presence of pyridine leads to formation of a mixture of novel N-thioaroyl-5-hydroxy-2H,5H-pyrano[3,2-с]chromen-2-one-3-carboxamides and 2-aryl-5-(4′-oxochromen-3′-yl)-6,7-dihydro-4H,5H-pyrano[2,3-d][1,3]thiazine-4,7-diones. The yields of these compounds clearly depend on the nature of the substituent on the 3-formylchromone and on the reaction conditions.