2‐Chloro‐4,5‐dihydroimidazole, III. Synthesis, Reactions, and Crystal Structure of 2‐(Alkylthio)‐7,8‐dihydroimidazo[1,2‐<i>a</i>]‐1,3,5‐triazine‐4(6<i>H</i>)‐thiones

Abstract

Abstract Treatment of 2‐chloro‐4,5‐dihydroimidazolium hydrogen sulfate ( 1 ) with ammonium thiocyanate results in the formation of 7,8‐dihydroimidazo[1,2‐ a ]‐1,3,5‐triazine‐2,4(3 H ,6 H )‐dithione ( 3 ), which undergoes selective alkylation under alkaline conditions to give 2‐(alkylthio)‐7,8‐dihydroimidazo[1,2‐ a ]‐1,3,5‐triazine‐4(6H)‐thiones 4a–f . 2‐Methylthio derivative 4a serves as a substrate for the synthesis of 2,3‐dihydroimidazo[1,2‐ a ]‐[1,2,4]triazolo[4,3‐ c ][1,3,5]triazine‐5(6 H )‐thione ( 7 ). The structure of 4c is proved by X‐ray analysis.