Search

A highly selective and practical asymmetric Ag(I) catalyst system has been developed for the [3 + 2] cycloaddition reactions between isocyanoacetates and cyclopentenediones. The current Ag(I) catalyst system tolerates moisture and air and readily utilizes class III solvents such as EtOAc and acetone. The development of on demandgeneration of an active chiral catalyst in the presence of isocyanides paves a way to the efficient asymmetric preparation of bicyclic pyrrolidines with four stereogenic centers, including two quaternary centers in 80–97% ee.

A rhodium-catalyzed decarbonylative aerobicoxidation of cyclic α-diketones has been developed for the first time, where the regioselective formations of α-pyrones and isocoumarins have been achieved. The current decarbonylative aerobicoxidation pathway proceeds via the C–C bond cleavage followed by a C–O bond formation, representing a biomimetic oxidation approach to unsaturated six-membered cyclic lactones. The unique ability of rhodium catalysts to induce the decarbonylative aerobicoxidation opens up a new synthetic toolbox that utilizes the “regioselective single carbon” extrusion strategy.

The direct conjugate addition reactions of imino esters to β-chlorovinyl ketones have been accomplished in the presence of a substoichiometric amount of hard base, LiHMDS. An in situgenerated species from the conjugate addition reaction readily acted as autocatalyst to convert the imino esters to its corresponding enolates. By utilizing a sequence of conjugate addition/elimination/lactonization followed by either reduction or reaction with amines, the novel one-pot syntheses of highly functionalized pyranone and pyrrole derivatives were accomplished in good to excellent yields.