1,4-Addition of o-naphthoquinone methides induced by silver-catalyzed cyclization of enynones: an approach to unsymmetrical triarylmethanes and benzo[f]chromenes

Abstract

The 1,4-addition reaction of ortho-naphthoquinone methide (o-NQM) intermediates induced by silver-catalyzed ring formation with electron-rich aromatic compounds and α-methylene ketones has been developed. This reaction provides an efficient method to construct versatile unsymmetrical triarylmethanes and benzo[f]chromenes under mild conditions. This transient intermediate was inseparable due to reversible dimerization but could be stored by forming a boric acid adduct for further transformations.