Generation of 4,6-dimethyl-5-[2-(2-methylprop-1-enyl)-1H-benzimidazol-1-yl]pyrimidine-2(5H)-thiones under kinetically controlled phase transfer catalysis conditions

The insertion of dimethylvinylidene carbene into azo moiety was investigated in order to synthesize 4,6-dimethyl-5-[2-(2-methylprop-1-enyl)-1H-benzimidazol-1-yl] pyrimidine-2(5H)-thiones [7a-j] under kinetically controlled phase transfer catalysis conditions. The reaction follows the pseudo-first order rate law. Rational mechanism of the reaction is proposed according to the experimental evidence. Effects of stirring speed, amount of catalyst and effect of temperature on the reaction rate were investigated in detail.