Functional masking of carbonyl group by 1-methyl-1H-imidazol-2-YL moiety

Easily obtained 1-methyl-2-(1′-hydroxyalkyl)-1H-imidazoles (4) were found to be a new type of masked form for carbonyl group which could survive under various severe conditions. The corresponding carbonyl compounds (3) were easily reproduced by quarternization of the imidazole (4) with CH₃I followed by aqueous basic treatment. 2-Acyl-1H-imidazoles (5) were convertible to aldehydes or ketones (3) by using the present methodology.