Carbon-carbon bond cleavage of alpha-hydroxybenzylheteroarenes to ketones and heteroarenes by catalytic action of cyanide ion based on retrobenzoin condensation

Treatment of 4-(alpha-benzyl-alpha-hydroxybenzyl)quinazoline (2a) with potassium cyanide in DMF resulted in carbon-carbon bond cleavage to give benzyl phenyl ketone (3a) and quinazoline (4). Similar results were obtained with other 4-(alpha-hydroxybenzyl)quinazolines (2b-f and 7a). This reaction proceeds through retrobenzoin condensation. This condensation also proceeded in pyrazolopyrimidine (9a) triazolopyrimidine (10a), quinoxaline (11a), and benzimidazole (12a), and the imidazolium salt (16) was an effective catalyst.