Rhodium-Catalyzed Asymmetric Formal Oleimation or Cycloaddition: 1,3-Dicarbonyl Compounds Reacting with 1,6-Diynes or 1,6-Enynes

摘要

Transition-metal-catalyzed asymmetric hydrogenation of enolizable β-ketoesters leading to β-hydroxyesters is a useful method for the one-step construction of two consecutive stereocenters. In this reaction, the ketone carbonyl group is enantioselectively reduced with hydrogen through C-H/O-H bond formation (Scheme 1). In contrast, asym- metric olefination or cycloaddition of the ketone carbonyl group of β-ketoesters through C=C or C-C/C—O bond formation would furnish chiral β,γ-unsaturated esters or β-alkoxyesters in a single step (Scheme 1). Despite potential synthetic utility of such reactions, no report has been found in the literature to date. In 2007 our research group reported that a cationic rhodium(I)/H8-binap complex is a highly active and versatile catalyst for the [2+2+2] cycloaddition of 1,2-dicarbonyl compounds with l,6-diynes. After this report, we succeeded using the cationic rhodium(I)/H8-binap complex as a catalyst in the asymmetric [2+2+2] cycloaddition of 1,2-dicarbonyl compounds with 1,6-enynes, thereby constructing two stereocenters with high enantio- and diastereoselectivity.We report herein the cationic rhodium(I)/H8-binap or segphos complex as a catalyst for the asymmetric formal olefination and cycloaddition of 1,3-dicarbonyl compounds with 1,6-diynes and 1,6-enynes, respectively, which construct one or three stereocenters with high diastereo- and enantioselectivity.