Endergonic addition of N-methylamines to aromatic ketones driven by photochemical offset of the entropic cost

Asymmetric Cross-Coupling of Aldehydes with Diverse Carbonyl or Iminyl Compounds by Photoredox-Mediated Cobalt Catalysis

The asymmetric cross-coupling of unsaturated bonds, hampered by their comparable polarity and reactivity, as well as the scarcity of efficient catalytic systems capable of diastereo- and enantiocontrol, presents a significant hurdle in organic synthesis. In this study, we introduce a highly adaptable photochemical cobalt catalysis framework that facilitates chemo- and stereoselective reductive cross-couplings between common aldehydes with a broad array of carbonyl and iminyl compounds, including N-acylhydrazones, aryl ketones, aldehydes, and α-keto esters. Our methodology hinges on a synergistic mechanism driven by photoredox-induced single-electron reduction and subsequent radical-radical coupling, all precisely guided by a chiral cobalt catalyst. Various optically enriched β-amino alcohols and unsymmetrical 1,2-diol derivatives (80 examples) have been synthesized with good yields (up to 90% yield) and high stereoselectivities (up to >20:1 dr, 99% ee). Of particular note, this approach accomplishes unattainable photochemical asymmetric transformations of aldehydes with disparate carbonyl partners without reliance on any external photosensitizer, thereby further emphasizing its versatility and cost-efficiency.

H2 O ⋅ B(C6 F5 )3 -Catalyzed para-Alkylation of Anilines with Alkenes Applied to Late-Stage Functionalization of Non-Steroidal Anti-Inflammatory Drugs

Anilines are core motifs in a variety of important molecules including medicines, materials and agrochemicals. We report a straightforward procedure that allows access to new chemical space of anilines via their para-C-H alkylation. The method utilizes commercially available catalytic H2 O ⋅ B(C6 F5 )3 and is highly selective for para-C-alkylation (over N-alkylation and ortho-C-alkylation) of anilines, with a wide scope in both the aniline substrates and alkene coupling partners. Readily available alkenes are used, and include new classes of alkene for the first time. The mild reaction conditions have allowed the procedure to be applied to the late-stage-functionalization of non-steroidal anti-inflammatory drugs (NSAIDs), including fenamic acids and diclofenac. The formed novel NSAID derivatives display improved anti-inflammatory properties over the parent NSAID structure.

Structural Simplification of Cryptolepine to Obtain Novel Antifungal Quinoline Derivatives against Phytopathogenic Fungi

A series of quinoline derivatives were designed and synthesized by the structural simplification of cryptolepine and evaluated for their fungicidal activity against six phytopathogenic fungi. Most of these compounds exhibited remarkable activities against Botrytis cinereain vitro. Among them, compounds A18 and L01 showed superior antifungal activity. Significantly, compared to cryptolepine, compound A18 exhibited broad-spectrum inhibitory activities against B. cinerea, Sclerotinia sclerotiorum, Rhizoctonia solani, Phytophthora capsica, Magnaporthe oryzae, and Fusarium graminearum with the respective EC₅₀ values of 0.249, 1.569, 3.915, 0.505, 0.246, and 4.999 μg/mL. Compound L01 displayed the best antifungal activity against B. cinerea with an EC₅₀ value of 0.156 μg/mL. Preliminary mechanistic studies showed that compound A18 could inhibit spore germination, affect the permeability of the cell membrane, increase the content of reactive oxygen species, and affect the morphology of hyphae and cells. Moreover, compound A18 showed excellent in vivo protective effect against B. cinerea, which was more potent than pyrimethanil and equitant to cryptolepine. These results evidenced that compound A18 displayed superior fungicidal activities and could be a potential fungicidal candidate against plant fungal diseases.

Energy- and atom-efficient chemical synthesis with endergonic photocatalysis

Endergonic photocatalysis is the use of light to perform catalytic reactions that are thermodynamically unfavourable. While photocatalysis has become a powerful tool in facilitating chemical transformations, the light-energy efficiency of these processes has not gathered much attention. Exergonic photocatalysis does not take full advantage of the light energy input, producing low-energy products and heat, whereas endergonic photocatalysis incorporates a portion of the photon energy into the reaction, yielding products that are higher in free energy than the reactants. Such processes can enable catalytic, atom-economic syntheses of reactive compounds from bench-stable materials. With respect to environmental friendliness and carbon neutrality, endergonic photocatalysis is also of interest to large-scale industrial manufacturing, where better energy efficiency, less waste and value addition are highly sought. We therefore assess here the thermochemistry of several classes of reported photocatalytic transformations to showcase current advances in endergonic photocatalysis and point to their industrial potential.

Visible Light-Mediated Enantioselective Addition of α-Aminoalkyl Radicals to Ketones Catalyzed by Chiral Oxazaborolidinium Ion

The development of a visible light-mediated synthetic method for chiral 1,2-amino tertiary alcohols is described. In the presence of a chiral oxazaborolidinium ion catalyst and photosensitizer, the enantioselective addition of an α-aminoalkyl radical to aryl methyl ketones under visible light provides chiral 1,2-amino tertiary alcohol derivatives in high yields (up to 88%) with excellent enantioselectivities (up to 98% ee). With mechanistic studies such as radical trapping analysis, radical clock analysis, and the measurement of quantum yield, a plausible catalytic cycle is proposed.