Chao Wang

A ruthenium‐catalyzed formal hydrogenative coupling for the functionalization of naphthols has been developed, γ ‐naphthol‐substituted chiral alcohols were obtained with excellent enantioselectivities (27 examples, up to >99% ee). The products could serve as synthons for the preparation of chiral oxygen‐containing heterocycles. Mechanistic studies indicate that the transformation proceeds through a base‐promoted conjugate addition to generate a ketone intermediate, which subsequently undergoes asymmetric hydrogenation.

Photoinduced transition metal catalysis offers innovative strategies for fostering novel chemical reactions and improving established ones. In this work, we present a highly efficient, photoinduced Mn(II)-bipyridine catalyzed C–N, C-O and C-S coupling reaction between aryl halides—particularly less reactive aryl chlorides—and nucleophiles containing nitrogen, oxygen, and sulfur. This protocol does not need an external photocatalyst, as the single Mn(II)–bipyridine complex simultaneously serves as both the light-harvester and the metal catalyst. This method exhibits excellent substrate scope, covering eight different nitrogen sources for C-N coupling, as well as C-O coupling with alcohols, C-S coupling with thiophenols, encompassing more than 150 examples, with yields reaching up to 94%. Mechanistic studies suggest that this reaction may be initiated and sustained by the Mn(I) species through the photoinduced homolysis of the catalyst precursor bipyridine-Mn(II)(OAc) ₂ , likely proceeding via a Mn(I)/Mn(III) catalytic cycle.

A cobalt pincer complex has been designed, synthesized, and successfully applied to catalytic asymmetric hydrogenation of quinolines under mild conditions. Containing a PNN ligand that features both a P and a C-stereogenic center, the cobalt catalyst allows for the hydrogenation of a variety of quinolines to afford chiral 1,2,3,4-tetrahydroquinolines with high yields and excellent enantioselectivities in general (51 examples, up to 99.9% ee). Probe reactions and DFT calculations suggest that the hydrogenation proceeds via a stepwise 1,2-1,2-hydride transfer pathway. The results obtained could provide a valuable hint for the development of more efficient 3d transition metal catalysts for asymmetric catalysis.

Oximes are used in many scientific and industrial domains, ranging from organic synthesis through biotechnology to materials science. Traditionally, their synthesis necessitates the use of hydrocarbons with specific functional groups, such as carbonyls, which are often more challenging and expensive to obtain compared to their non-functionalized counterparts. Here we introduce an approach that enables the synthesis of oximes from hydrocarbons via the oxidative oximation of methylene C-H bonds — the most prevalent molecular unit in the world of molecules. Under the catalysis of a manganese complex with hydrogen peroxide as the oxidant and hydroxylamine sulfate as the amine source, we demonstrate that a diverse array of molecules — from simple chemicals like propane and cyclohexane to complex compounds such as the antimalarial drug artemisinin — can be oximated at methylene C-H bonds with synthetically significant yields under mild conditions. The catalyst displays a good level of functionality tolerance and often predictable site selectivity in complex molecule settings. Our approach opens an avenue for oxime synthesis and is anticipated to have broad applications in the production of fine and commodity chemicals, bioactive molecules, and new materials.

Combining transition-metal catalysis with photocatalysis has emerged as a valuable, complementary approach for achieving carbon–heteroatom cross-coupling reactions. However, the need to use blue or high-energy near-UV light leads to problems with scalability, chemoselectivity, and catalyst deactivation, which have limited the synthetic applications of this combination. Herein, we report a method for red-light-driven nickel-catalyzed cross-coupling reactions of aryl halides with 11 different types of nucleophiles using a polymeric carbon nitride (CN-OA-m) as a photocatalyst. This semiheterogeneous catalyst system enabled the formation of four different types of carbon–heteroatom bonds (C–N, C–O, C–S, and C–Se) with a wide range of substrates (more than 200 examples) with yields up to 94%. Moreover, the photocatalyst is easily recovered and recycled, which makes it a promising new tool for the development of other reactions involving red-light metallaphotoredox catalysis.

The use of hydrazones as carbanion equivalents for carbon-carbon bond formation reactions has emerged as a versatile tool for organic synthesis. However, the enantioselective formation of carbon-carbon bonds with hydrazones has been underdeveloped. We have developed a Ru-catalyzed enantioconvergent hydrobenzylation of racemic allylic alcohols using aryl hydrazones as latent alkyl nucleophiles. The reaction produces enantioenriched products with two remote chiral centers, achieving high diastereoselectivities (up to 20:1 dr) and excellent enantioselectivities (99% ee in most cases). Notably, the alkyl source originates from the electrophilic sp² carbons of hydrazones, which are readily prepared from various aldehydes and depart from the most often employed alkyl nucleophiles derived from organometallic sp³ carbons, and the reaction releases harmless N₂ as the sole byproduct. Mechanistic investigations suggest a sequential dehydrogenation/conjugate addition/reduction pathway with a single Ru complex catalyzing both the borrowing hydrogen and hydrazone conjugate addition cycles while simultaneously controlling the stereoselectivities of both chiral centers. DFT studies reveal that the Ru complex acts as a metal-ligand bifunctional catalyst, activating the hydrazones, reversing the C═N bond polarity, and facilitating the conjugate addition. The key transition state of the bond formation step features the attack of the activated hydrazone on an α,β-unsaturated ketone in an outer-sphere manner, offering a new catalytic mode for hydrazone chemistry.

Chiral ruthenium(ii) complexes featuring a single labile coordination site and cyclometallation were successfully synthesized and demonstrated to be highly effective catalysts for the asymmetric reduction of aminoketones.

Oximes are used in many scientific and industrial domains, ranging from organic synthesis through biotechnology to materials science. Traditionally, their synthesis necessitates the use of hydrocarbons with specific functional groups, such as carbonyls, which are often more challenging and expensive to obtain compared to their non-functionalized counterparts. Here we introduce a new approach that enables the direct synthesis of oximes from hydrocarbons via the oxidative oximation of methylene C-H bonds — the most prevalent molecular unit in the world of molecules. Under the catalysis of a manganese complex with hydrogen peroxide as the oxidant and hydroxylamine sulfate as the amine source, we demonstrate that a diverse array of molecules — from simple chemicals like propane and cyclohexane to complex compounds such as the antimalarial drug artemisinin — can be oximated at methylene C-H bonds with synthetically significant yields under mild conditions. The catalyst displays a good level of functionality tolerance and often predictable site selectivity in complex molecule settings. Our approach opens new avenues for oxime synthesis and is anticipated to have broad applications in the production of fine and commodity chemicals, bioactive molecules, and new materials.