Reactions of 4‐chloro‐5h‐1,2,3‐dithiazole‐5‐thione with α,β‐unsaturated β‐amino esters: Formation of 2‐[2‐(1‐alkenylsulfanyl‐1‐alkoxycarbonyl‐2‐amino)‐1,2‐dicyano‐vinylsulfanyl]‐3‐amino‐2‐alkenoic alkyl esters

Abstract

Treatment of 4-chloro-5H-1,2,3-dithiazole-5-thione with alkyl 3-alkyl (or aryl)-3-amino-2-propenoates in the presence of pyridine (2 equivalents) in dichloromethane at reflux gave 2-[2-(1-alkenylsulfanyl-1-alkoxycarbonyl-2-amino)-1,2-dicyanovinylsulfanyl]-4 and -1,2-dicyanovinyldisulfanyl]-3-amino-2-alkenoic alkyl esters 7 in 16 to 60% and 8 to 48% yields, respectively.