GAS-PHASE PYROLYSIS IN HETEROCYCLIC SYNTHESIS - GAS-PHASE ELIMINATION-REACTIONS OF SOME SUBSTITUTED AMINOAZOLES

Gas-phase pyrolyses of ethyl N-(5-cyanomethyl-1,3,4-thiadiazol-3-yl)ca rbamate (1), 1-benzoyl-3-(3-methylpyrazol-5-yl)thiourea (2), 1-benzoyl -3-(5-methylisoxazol-3-yl)thiourea (3), and 1-acetyl-3-(3-phenylpyrazo l-5-yl)thiourea (4) have been studied. These reactions were homogeneou s and unimolecular. The kinetics obeyed the first-order rate equation. Utilization of this pyrolytic reaction in heterocyclic synthesis is c onsidered and mechanistic information has been obtained from kinetic d ata and product analysis using an on-line pyrolysis GC-MS technique. T he physical constants of four new substituted aminoazoles are also des cribed. (C) 1997 John Wiley & Sons, Inc.