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Chiral amines are valuable building blocks in the manufacture of agrochemicals, pharmaceuticals, natural products, fine chemicals, functional materials among others. Compared to asymmetric hydrogenation of imines/enamides and biocatalytic/organocatalytic asymmetric reductive amination, transition metal catalyzed direct asymmetric hydrogenative amination reactions (DAHA) using molecular dihydrogen as the reductant are highly economical, atom and/or step‐efficient and thus attractive for researchers from both industry and academia. In previous reviews, catalysts/methods development, applications in synthesis of pharmaceuticals and [N] source were summarized and discussed. In this review, we summarize and discuss the ketone substrates scope upon utilizing the state‐of‐the‐art transition metal catalysts. The substrate limitations, potential applications and key mechanisms are also critically concluded. [ABSTRACT FROM AUTHOR]

Heterogeneous photocatalysis has emerged as a powerful and sustainable technique in organic synthesis; however, the application of graphitic carbon nitride (g-C3N4) as a heterogeneous photocatalyst for organic transformations is still in its infancy. The development of novel organic transformations catalyzed by g-C3N4 is actively being pursued by chemists but it remains challenging. Herein, we describe a visible-light-driven g-C3N4-catalyzed atom transfer radical addition (ATRA) of alkynes to synthesize valuable (E)-β-thio/seleno vinylsulfones. This approach features heterogeneous photocatalysis, excellent regio- and stereoselectivities, 100% atom economy, a metal- and additive-free nature, and broad substrate scope covering (hetero)aryl and alkyl alkynes, especially the industrial feedstock propyne. Furthermore, this method can be applied to the late-stage functionalization of complex molecules. Notably, g-C3N4 can be recovered and reused in five runs without loss of catalytic activity. Mechanistic studies demonstrate that the reaction occurs via an energy transfer process rather than single electron transfer. [ABSTRACT FROM AUTHOR]

Arene hydrogenation is the most straightforward method to prepare carbo‐ and heterocycles. However, the high resonance energy prevents aromatic substrates from hydrogenation. Herein the homogeneous, nucleophilic hydrogenation of less electron‐rich arenes and heteroarenes is reported. The Co(P4N2)H species that has been demonstrated to be a strong hydride donor could deliver a hydride ion to the cyano (hetero)arene substrates. Deuterium labeling experiments supported a Michael‐type reaction pathway. Theoretical analyses have been conducted to investigate the hydricity of the catalytically active CoH species and the electrophilicity of the arene substrates. An outlook for the synthesis of more challenging substituted benzenes was proposed based on the in silico modification of the CoH species. [ABSTRACT FROM AUTHOR]

Arene hydrogenation is the most straightforward method to prepare carbo- and heterocycles. However, the high resonance energy prevents aromatic substrates from hydrogenation. Herein the homogeneous, nucleophilic hydrogenation of less electron-rich arenes and heteroarenes is reported. The Co(P 4 N 2 )H species that has been demonstrated to be a strong hydride donor could deliver a hydride ion to the cyano (hetero)arene substrates. Deuterium labeling experiments supported a Michael-type reaction pathway. Theoretical analyses have been conducted to investigate the hydricity of the catalytically active CoH species and the electrophilicity of the arene substrates. An outlook for the synthesis of more challenging substituted benzenes was proposed based on the in silico modification of the CoH species., (© 2022 Wiley-VCH GmbH.)

We have developed a method for recyclable hypervalent-iodine-mediated direct dehydrogenative α,β'- bifunctionalization of β-ketoesters and β-diketones under metal-free conditions, which affords a straightforward way to synthesize benzo-fused 2,3-dihydrofurans. This efficient, mild method, which has a wide substrate scope and good functional-group tolerance, was used for the multistep synthesis of the protected aglycone of a naturally occurring phenolic glycoside. A mechanism involving Michael addition to an enone intermediate and subsequent oxidative cyclization is proposed., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)