Generation of iminyl radicals through sulfanyl radical addition to vinyl azides

Benzenethiol and 2-benzo[b]thiophenethiol undergo almost instantaneous reaction with alpha-azidostyrene and 1-azido-trans-stilbene in benzene, at room temperature, to give corresponding beta-sulfanylated imines and enamines in virtually quantitative yield. With alpha-azidostyrene, phenethyl and allyl mercaptan are found to react in a similar fashion, but to rates very much lower. Results are interpreted in terms of radical-chain reactions involving intermediacy of 2-sulfanyliminyl radicals which could result from sulfanyl radical attack at the azide beta-carbon followed by nitrogen extrusion by the ensuing radical adduct.