Ruthenium-Catalyzed Enantioselective Carbon−Carbon Bond Forming Reaction via Allenylidene-Ene Process: Synthetic Approach to Chiral Heterocycles Such As Chromane, Thiochromane, and 1,2,3,4-Tetrahydroquinoline Derivatives

Our previously disclosed ruthenium-catalyzed carbon-carbon bond forming reactions between propargylic alcohols and alkenes via an allenylidene-ene type pathway have been successfully applied to an enantioselective intramolecular cyclization for a variety of chiral heterocycles such as chromane, thiochromane, and 1,2,3,4-tetrahydroquinoline derivatives (up to 99% ee) by use of a suitable optically active diruthenium complex as a catalyst. The methodology described in this paper becomes a novel synthetic approach to chiral heterocycles, the structures of which are widely found in many natural and biologically active compounds.