A Novel Entry toward 2-Imino-1,3-thiazolidines and 2-Imino-1,3-thiazolines by Ring Transformation of 2-(Thiocyanomethyl)aziridines

摘要

A new,efficient,and straightforward synthesis of 3-arylmethyl-4-chldromethyl-2-imino-1,3-thiazolidines and 2-(N-acylimino)-3-arylmethyl-4-chloromethyl-1,3-thiazolidines has been developed by ring transformation of l-arylmethyl-2-(thiocyanomethyl)aziridines upon treatment with a catalytic amount of titanium(IV)chloride in dichloromethane.The latter 2-(thiocyanomethyl)-aziridines were prepared in high yields from l-arylmethyl-2-(bromomethyl)aziridines by reaction with potassium thiocyanate in DMF.The 2-imino-1,3-thiazolidines and 2-(N-acylimino)-1,3-thiazolidines thus obtained can be easily interconverted,either by treatment with an acid chloride and a base in ether toward 2-(N-acylimino)thiazolidines or by treatment with potassium carbonate in methanol toward N-deprotected 2-iminothiazolidines.Dehydrohalogenation of 2-(N-acylimino)-3-arylmethyl-4-chloromethyl-1,3-thiazolidines by means of potassium tert-butoxide in DMSO afforded 2-(N-acylimino)-4-methyl-2,3-dihydro-1,3-thiazolines in good yields.