A new improved method for the synthesis of 2,4-diarylpyrimidines starting from 2,2,2-trichloroethylideneacetophenones

An advantageous new approach to 2,4-diarylpyrimidines has been developed. 2,2,2-Trichloroethylideneacetophenones reacted with benzamidines leading to novel 2,6-diaryl-6-hydroxy-4-trichloromethyl-1,4,5,6-tetrahydropyrimidines in near quantitative yields. These compounds were efficiently dehydrated to obtain previously unknown 2,4-diaryl-6-trichloromethyl-1,6-dihydropyrimidines, which were able to undergo aromatisation via chloroform elimination to give 2,4-diarylpyrimidines in high yields. A main improvement of this procedure lies in circumventing the oxidative dehydrogenation of dihydropyrimidine intermediates. This preparative process has also been adapted to a one-pot protocol.