Two methods for the preparation of anilinopyrylium salts are described. The conversion of these salts to pyrans, pyridines, and nitrobenzenes is discussed. Azepines, benzimidazoles, and benxotriazoles are readily obtained from the o‐aminoanilinopyrylium salts.

The 6‐(3‐hydroxypropylamino)‐3‐methylpyrimidine‐2,4‐dione (1) did not afford the expected 6‐(3‐chloro‐propylamino)‐ derivative on reaction with thionyl chloride, but, instead, the pyrimidine rings were joined via a sulfur bridge to give 9,9′‐thiobis(1,2,3,4,7,8‐hexahydro‐7‐melnyl‐6H‐pyrimido[1,6‐a]pyrirnidine‐6,8‐dione) (3). An identical 9,9′‐thiobis‐ derivative 3 was obtained when reacting thionyl chloride with 1,2,3,4,7,8‐hexahydro‐7‐methyl‐6H‐pyrimido[1,6‐a]pyrimidine‐6,8‐dione (4). We suppose the sulfoxide‐ derivative 2 to be the intermediate of both routes: it underwent reduction to the final sulfide 3 in excess thionyl chloride.