The Reaction of DABCO with 4-Chloro-5H-1,2,3-dithiazoles: Synthesis and Chemistry of 4-[N-(2-Chloroethyl)piperazin-1-yl]-5H-1,2,3-dithiazoles.

N-(4-Chloro-5H-1,2,3-dithiazol-5-ylidene)anilines react with DABCO in hot PhCl to give N-{4-[N-(2-chloroethyl)piperazin-1-yl]-5H-1,2,3-dithiazol-5-ylidene}anilines in high yields (70-92%). The reaction also works with 4-chloro-5H-1,2,3-dithiazol-5-one and -thione, giving the corresponding products in 85% and 76% yields, respectively. While the reaction of several (4-chloro-5H-1,2,3-dithiazol-5-ylidene)methanes with DABCO failed to give {4-[N-(2-chloroethyl)piperazin-1-yl]-5H-1,2,3-dithiazol-5-ylidene}methanes, these can be prepared in moderate yields via classical cycloaddition-retrocycloaddition strategies from 4-[N-(2-chloroethyl)piperazin-1-yl]-5H-1,2,3-dithiazole-5-thione. The 2-chloroethyl moiety on selected dithiazoles was also modified without cleavage of the 1,2,3-dithiazole by reaction with various nucleophiles, giving access to 4-[N-(2-substituted)piperazin-1-yl]-5H-1,2,3-dithiazoles in moderate to high yields.