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

Flash vacuum pyrolysis of the allyl ethers 9-11 and of the oxime ethers 15-17 at 650 degrees C (5 x 10(-2)-5 x 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 beta-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.