Cascade synthesis of 2-amino-5-(4-methoxyphenyl)-4-phenyl-1,3-thiazole by reaction of 4-chloro-N-[2,2-dichloro-1-(4-methoxyphenyl)-2-phenylethyl]benzenesulfonamide with thiourea
摘要:
4-Chloro-N-[2,2-dichloro-1-(4-methoxyphenyl)-2-phenylethyl]benzenesulfonamide reacted with thiourea on heating in DMF in the presence of sodium carbonate to give 5-(4-methoxyphenyl)-4-phenyl-1,3-thiazole-2-amine. A probable reaction scheme includes cyclization of the initial N-dichloroethyl amide to N-sulfonyl-2,3-diaryl-2-chloroaziridine which undergoes isomerization with opening of the three-membered ring to 1-arylsulfonylamino-2-chloro-2-(4-methoxyphenyl)-1-phenylethene. The subsequent heterocyclization in the reaction with thiourea is accompanied by aromatization via elimination of the arenesulfonamide fragment.
N-[1-4-Methoxyphenyl-2-phenyl-2,2-dichloroethyl]arenesulfonamides are formed in reaction of N-(2-phenyl,-2.2-dichloroethylidene)-4-chlorobenzenesulfonamide and N-(2-phenyl-2,2-dichloroethylidene)-4-methylbenzenesulfonamide with anisole catalyzed by boron trifluoride etherate, and in reaction of anisole with 1,1-di(arenesulfonamido)-2-phenyl-2,2,-dichloroethanes in the presence of concentrated sulfuric acid.