Partial reduction of active amides to aldehydes by tri-n-butyltin hydride

Abstract

1-Acyl-3-methylimidazole-2-thiones, easily prepared from acid chlorides and 2-mercapto-1-methylimidazole were reduced to the corresponding aldehydes with tri-n-butyltin hydride in refluxing toluene. The aldehydes were obtained in good yields. The present method appeares to be applicable to the synthesis of aldehydes from both aliphatic and aromatic acid derivatives having functional groups such as nitro, double bond and carbonyl group. These partial reductions may occur via a nonradical mechanism. Other active amides and esters such as 3-acylthiazolidine-2-thiones, N-acylimidazoles, S-2-pyridyl thioesters, 2-pyridyl esters did not work well with tri-n-butyltin hydride.