Homogeneous palladium-catalyzed asymmetric hydrogenation

Abstract

The transition metal catalyzed asymmetric hydrogenation of unsaturated compounds arguably presents one of the most attractive methods for the synthesis of chiral compounds. Over the last few decades, Pd has gradually grown up as a new and popular metal catalyst in homogeneous asymmetric hydrogenation the same as traditional Ru, Rh and Ir catalysts. Much progress has been successfully achieved in the asymmetric reduction of imines, enamines, olefins, ketones and heteroarenes. It was also found that palladium catalyzed asymmetric hydrogenation could be used as a key step in tandem reactions to quickly synthesize chiral compounds. This tutorial review intends to offer an overview of recent progress in homogeneous palladium catalyzed asymmetric hydrogenation and should serve as an inspiration for further advances in this area. Key learning points(1) The general mechanism for homogeneous palladium catalyzed asymmetric hydrogenation.(2) The palladium catalysts' tolerance against acid, water and air in the hydrogenation process.(3) The substrate scopes and limitations in these transformations. (4) The common hydrogen sources used in these catalytic systems.(5) The general solvent-dependent phenomena in these transformations.

Homogenous Pd-Catalyzed Asymmetric Hydrogenation of Unprotected Indoles: Scope and Mechanistic Studies

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Functionalized Magnetic Mesoporous Silica Nanoparticle‐Supported Palladium Catalysts for Carbonylative Sonogashira Coupling Reactions of Aryl Iodides

“…Of the transition metal catalysts, palladium is arguably the most widely utilized in organic transformations, including oxidation, [1] alkylation, [2] hydrogenation, [3] hydroformylation, [4] carbonylation, [5] and cross-coupling reactions.…”

An easily recoverable and recyclable homogeneous polyester-based Pd catalytic system for the hydrogenation of α,β-unsaturated carbonyl compounds

“…The selective reduction of α,β-unsaturated carbonyl compounds by means of molecular hydrogen in the presence of catalysts still remains an intriguing challenge in catalysis [2]. The selectivity, including enantioselectivity, strongly depends on the nature of the active metal catalyst [3] and on the reaction conditions [4]. Homogeneous catalysts often present good activity and selectivity, but the major drawback of homogeneous processes is the separation of the precious catalyst from the product mixture that requires an energy intensive process such as distillation.…”