The Rhodium-Catalyzed Carbene Cyclization Cycloaddition Cascade Reaction of Vinylsulfonates

Vinylsulfonates have proved to be excellent dipolarophiles for carbonyl ylides derived from diazoketones in rhodium-catalyzed intramolecular cycloadditions. Polyfunctional substrates, such as 8 and (+)-15, were readily available from hydroxy esters, e.g. 1 and the cyclopenta-1,3-dione 10, respectively, and the resulting polycyclic sultones were formed under mild reaction conditions in high yields with very good diastereoselectivities. A ruthenium-catalyzed asymmetric transfer hydrogenation was found to desymmetrize the meso-cyclopenta-1,3-dione 12 efficiently.