Highly efficient trapping of the Nazarov intermediate with substituted arenes.

1,4-Dien-3-ones bearing pendant arylethyl side chains were readily prepared from substituted dihydrocinnamaldehydes. When treated with TiCl(4) at low temperature, these compounds underwent domino cyclization to give benzohydrindenones in near-quantitative yield and with complete diastereoselectivity. Reaction: see text.