Solvent-Controlled Diastereodivergent Synthesis of Hexahydropyrrolo[2,1-]isoquinolines through Pd/C-Catalyzed Dehydrogenative [3 + 2] Cycloaddition.

A Pd/C-catalyzed dehydrogenative [3 + 2] cycloaddition is described for the diastereoswitchable synthesis of hexahydropyrrolo[2,1-]isoquinolines by altering solvents. The reaction proceeds through a sequential Pd/C-catalyzed dehydrogenative formation of azomethine ylides from tetrahydroisoquinoline acetates and 1,3-dipolar cycloaddition with 2-nitroethenylbenzenes. This method displayed tunable diastereoselectivity, a broad substrate scope and good functional group compatibility.

Gold/Chiral Amine Relay Catalysis Enables Asymmetric Synthesis of C2-Quaternary Indolin-3-ones.

A mild and effective strategy for the asymmetric synthesis of C2-quaternary indolin-3-ones from 2-alkynyl arylazides and ketones by gold/chiral amine relay catalysis is described. In this reaction, 2-alkynyl arylazides undergo gold-catalyzed cyclization, nucleophilic attack, and oxidation to form intermediate 2-phenyl-3-indol-3-ones, followed by an l-proline-catalyzed asymmetric Mannich reaction with ketones, to afford corresponding products in satisfactory yields with excellent enantio- and diastereoselectivities.