Construction of Polyfunctionalized 6-5-5 Fused Tricyclic Carbocycles via One-Pot Sequential Semipinacol Rearrangement/Michael Addition/Henry Reaction.

A novel one-pot semipinacol rearrangement/Michael addition/Henry reaction of vinylogous α-ketols with nitroolefins has been achieved through the promotion of two Lewis acids, namely, TMSOTf and TiCl4, at temperatures between 0 and -78 °C. A range of synthetically challenging polyfunctionalized 6-5-5 and 7-5-5 fused tricyclic carbocycles bearing up to five continuous stereocenters, including one quaternary carbon center, are rapidly constructed in moderate to good yields with good to high diastereoselectivities in most cases.