Ethonam

2-Aminotetralin () is alkylated with ethyl chloroacetate to afford the glycine derivative. Heating with formic acid then affords the amide (2). This compound is then reacted with ethyl formate to yield hydroxymethylene ester (3). Reaction with isothiocyanic acid gives the imidazole-2-thiol (5). The sequence may first involve hydrolysis of the formamido group, followed by addition of the amine to isothiocyanic acid; cyclization of the thiourea nitrogen with the formyl function would complete formation of the heterocycle. Desulfurization by means of Raney nickel finishes the synthesis of ethonam (6).