2-Trifluoromethyl-1,3-diazabutadienes as Useful Intermediates for the Construction of 2-Trifluoromethylpyrimidine Derivatives

A methodology to prepare 2-trifluoromethylpyrimidines has been developed on the basis of a cyclization reaction of 2-trifluoromethyl-1,3-diazabutadienes. These 2-trifluoromethyl-1,3-diazabutadienes were prepared by the condensation of trifluoroacetamidine and amide acetals or with chloromethaniminium salt derived from N , N -dimethylbenzamide with phosphorus oxychloride. The cycloaddition reactions of these 2-trifluoromethyl-1,3-diazabutadienes with DMAD and phenylacetyl chloride provided 2-trifluoromethylpyrimidine derivatives in regular to moderate overall yield.