Pyrolysis of phenylalkylsulphonyl azides and 2-phenethyl azidoformate. Selectivity of sulphonylnitrenes and contrast between sulphonyl- and carbonyl-nitrenes

Abstract

Flash vacuum pyrolysis and solution thermolysis of Ph[CH₂]_nSO₂N₃ indicate that intramolecular addition to the phenyl group is preferred in solution, provided that up to an eight-membered sultam ring is formed, otherwise side-chain insertion results, while in the gas phase the latter process is favoured when n= 4,5, but not 3; some 5,6,7,8-tetrahydroquinoline is obtained when n= 3 at 990 °C, but 2-phenethyl azidoformate gave monomeric tetrahydro-1, 3-oxazino [3,4-a] azepin-2-one and 4-phenyl-oxazolidinone, but no dihydrocyclopenta [b] pyridine, even at 990 °C.