Mechanism and origins of ligand-controlled Pd(ii)-catalyzed regiodivergent carbonylation of alkynes

Recent advances in ligand-enabled palladium-catalyzed divergent synthesis

Developing efficient and straightforward strategies to rapidly construct structurally distinct and diverse organic molecules is one of the most fundamental tasks in organic synthesis, drug discovery and materials science. In recent years, divergent synthesis of organic functional molecules from the same starting materials has attracted significant attention and has been recognized as an efficient and powerful strategy. To achieve this objective, the proper adjustment of reaction conditions, such as catalysts, solvents, ligands, etc., is required. In this review, we summarized the recent efforts in chemo-, regio- and stereodivergent reactions involving acyclic and cyclic systems catalyzed by palladium complexes. Meanwhile, the reaction types, including carbonylative reactions, coupling reactions and cycloaddition reactions, as well as the probable mechanism have also been highlighted in detail.

Ligand-Controlled Palladium-Catalyzed Asymmetric [4+3] and [2+3] Annulation Reactions of Spirovinylcyclopropyl Oxindoles with o-Quinone Methides

We herein report regiodivergent ligand-controlled palladium-catalyzed asymmetric cycloaddition reactions between spirovinylcyclopropyl oxindoles and o-quinone methides. Specifically, by using the chiral P,P-ligand Segphos (L5), we obtained various spirooxindole-3,4-benzo[b]oxepanes in moderate to good yields with excellent enantioselectivities via [4+3] cycloaddition reactions. In contrast, reactions involving Trost's ligand (L7) showed different regio- and stereoselectivities, affording bispirooxindole heterocyclic compounds in good yields via [2+3] cycloaddition reactions.

Ligand-Controlled Regiodivergence for Catalytic Stereoselective Semireduction of Allenamides

Ligand-controlled regiodivergence has been developed for catalytic semireduction of allenamides with excellent chemo- and stereocontrol. This system also provides an example of catalytic regiodivergent semireduction of allenes for the first time. The divergence of the semireduction is enabled by ligand switch with the same palladium pre-catalyst under operationally simple and mild conditions. Monodentate ligand XPhos exclusively promotes selective 1,2-semireduction to afford allylic amides, while bidentate ligand BINAP completely switched the regioselectivity to 2,3-semireduction, producing (E)-enamide derivatives.

Diverse synthesis of pyrrolo/indolo[3,2-c]coumarins as isolamellarin-A scaffolds: a brief update

This review presents a different synthetic approach of pyrrolo/indolo[3,2-c]coumarins via classical reactions including metal-catalyzed and green reaction protocols.