Polyfunctional Aliphatic Compounds. IV. The Cyclization of Nitriles by Halogen Acids. A New Synthesis of Thiazoles

α-Cyanoalkyl thiocyanates, prepared from α-chloroalkyl and α-(4-toluenesulfonyloxy)alkyl cyanides, are shown to undergo cyclization to derivatives of 2-bromo-4-aminothiazole by means of hydrogen bromide. Hydrogen chloride is unsatisfactory as a cyclizing agent whereas hydrogen iodide causes further reduction and leads directly to derivatives of the previously inaccessible 4-aminothiazoles. Attempts to apply this synthesis to the preparation of selenazoles were unsuccessful.