A study of the gas-phase interconversion of 1-(2-aryloxyphenyl)alkaniminyl and 2-(aryliminomethyl)phenoxyl radicals

Abstract

Flash vacuum pyrolysis of the allyl ethers 9–11 and of the oxime ethers 15–17 at 650 °C (5 × 10^–2–5 × 10^–3 Torr) generates 2-(aryliminomethyl)phenoxyl radicals 4 and 1-(2-aryloxyphenyl)alkaniminyl radicals 5 respectively which can interconvert via a spirodienyl radical leading to common products which are generally isolated in low to moderate yield. The iminyls 5 normally undergo β-cleavage leading to nitriles (e.g. 21) and/or to benzofurans (e.g. 22) after cyclisation. The phenoxyls 4 show more complex behaviour dominated by hydrogen abstraction processes leading to products such as phenols (e.g. 32), the indole 27 or phenanthridines 34 and 35.