“…In particular, we and collaborators have disclosed several radical addition–annulation–difunctionalization of 1,6-enynes for multiple ring formations (Scheme a) . Zhu and co-workers pioneered the preparation of a novel class of enynones by adjusting the carbonyl group position of 1,6-enynes and applied them as o -naphthoquinone methides ( o -NQMs) precursors to undergo intramolecular 6- exo - trig cyclization, leading to the formation of o -NQMs intermediate in the presence of silver catalysts, followed by o -NQMs’ [4 + 2] annulations with styrene to generate benzo[ h ]chromanes (Scheme b, path i ) . Moreover, o -NQMs could be trapped by electron-rich aromatic compounds (1,3,5-trimethoxybenzene, 1,2,3-trimethoxybenzene, 1-naphthol, and 2-naphthol) or heteroaryl compounds (indoles and tetronic acid-derived enamino lactones) to give unsymmetrical triarylmethanes through 1,4-conjugate addition (Scheme b, path ii ) .…”