Asymmetric (Transfer) Hydrogenation of Functionalized Alkenes During the Past Decade

Asymmetric Full Saturation of Vinylarenes with Cooperative Homogeneous and Heterogeneous Rhodium Catalysis

“…Seeking the development of an asymmetric hydrogenation of arenes, initial studies on the reactivity of rhodium catalysts demonstrated that common rhodium precursors in the form of [Rh­(COD) 2 ]­X (X = anion) aggregate into very reactive nanoparticles for the hydrogenation of substituted benzenes (Figure a). We realized that the exact same precursors are frequently used for the homogeneous rhodium-diphosphine-catalyzed asymmetric hydrogenation of olefins, which is one of the most studied types of asymmetric hydrogenation. , Notably, although some neutral rhodium complexes (such as [Rh­(COD)­Cl] 2 and [Rh­(η 5 -C 5 Me 5 )­Cl 2 ] 2 , ) were found as effective precatalysts for dearomative (transfer) hydrogenations, the duality of commonly used cationic rhodium precursors ([Rh­(COD) 2 ]­X) has not been reported so far. The active catalyst in these homogeneous asymmetric hydrogenations is normally formed in situ by mixing a rhodium-precursor and diphosphine ligand.…”

“…We realized that the exact same precursors are frequently used for the homogeneous rhodium-diphosphine-catalyzed asymmetric hydrogenation of olefins, which is one of the most studied types of asymmetric hydrogenation. 6,27 Notably, although some neutral rhodium complexes (such as [Rh(COD)Cl] 2 28 and [Rh(η 5 -C 5 Me 5 )Cl 2 ] 2 29,30 ) were found as effective precatalysts for dearomative (transfer) hydrogenations, the duality of commonly used cationic rhodium precursors ([Rh(COD) 2 ]X) has not been reported so far. The active catalyst in these homogeneous asymmetric hydrogenations is normally formed in situ by mixing a rhodium-precursor and diphosphine ligand.…”

“…Catalysis plays a fundamental and key role in organic synthesis and is used as a tool for the production of numerous pharmaceuticals, natural products, agrochemicals, and fine chemicals. , Homogeneous and heterogeneous catalyzed hydrogenation constitute two well-developed areas in both industry and academia and have independently been awarded shares of Nobel prizes (1912, Sabatier; 2001, Noyori and Knowles). − Over the past decades, rhodium has emerged as a robust metal for homogeneous as well as heterogeneous catalyzed hydrogenation. The development of chiral ligands (mainly diphosphines) that in many cases are commercially available presently has driven and expanded homogeneous rhodium-catalyzed hydrogenation of diversely substituted olefins largely to become a powerful strategy for the production of optically active compounds (Figure a). , On the other hand, heterogeneous rhodium catalysts have been found to be reactive toward the hydrogenation of aromatic unsaturated bonds and applied therein (Figure. b) .…”

“…The development of chiral ligands (mainly diphosphines) that in many cases are commercially available presently has driven and expanded homogeneous rhodium-catalyzed hydrogenation of diversely substituted olefins largely to become a powerful strategy for the production of optically active compounds (Figure 1a). 6,7 On the other hand, heterogeneous rhodium catalysts have been found to be reactive toward the hydrogenation of aromatic unsaturated bonds and applied therein (Figure . 1b). 8 However, asymmetric hydrogenation of aromatic compounds is restricted to heteroaromatic rings and fused arenes, whereas the asymmetric hydrogenation of simple substituted benzenes remains a formidable goal.…”