Facile Conversion of Amino Acids into 1-Alkyl Imidazole-2-thiones, and Their Oxidative Desulfurization to Imidazoles with Benzoyl Peroxide

Abstract

Glycine was acylated with isothiocyanates and condensed to 3-alkyl 2-thiohydantoins, which were reduced with a mixture of sodium borohydride and lithium chloride and dehydrated to 1-alkyl imidazole-2-thiones. These were oxidatively desulfurized to imidazoles with benzoyl peroxide. No chromatography was required for model compounds. The methods developed were used to elaborate tyrosine to 1,4-di(p-methoxybenzyl)imidazole, a common intermediate in the syntheses of three imidazoles from the sponge Leucetta.