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Alkylation reactions are fundamental carbon‐carbon bond‐forming reactions in synthetic organic chemistry. Among them, intermolecular α‐alkylation reactions of carbonyl compounds with alkenes are important because they are more atom‐economical than the equivalent processes using alkyl halides. However, intermolecular reactions with nonactivated alkenes such as 1‐hexene, which can allow the use of a wide range of valuable substrates, have been considered to be very challenging for a long time. In this review, radical‐mediated intermolecular α‐alkylation reactions of carbonyl compounds with nonactivated alkenes are discussed. The examples are grouped into three types of reactions: peroxide‐mediated reactions, metal‐oxidant‐mediated reactions, and photoactivated reactions. Photoredox‐catalyzed alkylation reactions under visible‐light irradiation are discussed as a particularly promising recent hot topic. This review provides brief history and new prospects on the α‐alkylation process with nonactivated alkenes using α‐carbonyl radical species. [ABSTRACT FROM AUTHOR]

Water is not a good solvent for most organic compounds, yet water can offer many benefits to some organic reactions, hence enriching organic chemistry. Herein, the unique divergent reactivity of 2‐substituted indoles with ⋅NO sources is presented. The amount of water solvent was harnessed for a scalable, benign, and expedient synthesis of indolenine oximes, albeit with water's inability to dissolve the reactants. 2‐Methoxyethyl nitrite, which has been tailored for reactions in water, empowered this protocol by enhancing the product selectivity. We further report on chemoselective transformations of the products that rely on their structural features. Our findings are expected to offer access to an underexplored chemical space. The platform is also applicable to oximinomalonate synthesis. Mechanistic studies revealed the important role of water in the reversal of stability between oxime and nitroso compounds, promoting the proton transfer. [ABSTRACT FROM AUTHOR]

Here we show continuous‐flow synthesis of a key inter‐mediate of (S)‐Metolachlor, which is a widely used agrochemical that is in huge demand, with asymmetric hydrogenation using a heterogeneous catalyst immobilized on a core/shell‐type support. We have immobilized a homogeneous catalyst onto a core/shell‐type heterogeneous support that was developed in our laboratory, which showed high turnover frequency and turnover number over a long period (over 120 h) when used in a solvent‐free continuous‐flow manner. This result demonstrates the feasibility of continuous‐flow production of chiral agrochemicals with packed‐bed heterogeneous catalysts. Moreover, the heterogenization protocol was shown to be applicable to elaborate practical catalysts used in industry, especially the group of phosphine ligands. [ABSTRACT FROM AUTHOR]

Transition metal‐catalyzed enantioselective C−H bond functionalizations have become efficient methods for the synthesis of complex optically active molecules. Heterogeneous catalysts for this chemistry remain largely unexplored despite the advantages they offer in terms of ease of separation and reuse of catalysts. Herein, we report the development of heterogeneous chiral Rh catalysts for continuous‐flow enantioselective hydroacylations. Heterogeneous catalysts could be prepared simply by mixing supports and Rh complexes. The prepared catalysts exhibited excellent activity and enantioselectivity affording optically active ketones in quantitative yields with 99 % ee's. Under the optimized reaction conditions, a turnover number >300 was achieved without the leaching of Rh species. The catalysts exhibited a wide substrate scope and in sequential‐flow reactions with other heterogeneous catalysts, the syntheses of biologically active molecules and functional materials were demonstrated. [ABSTRACT FROM AUTHOR]

Photoinduced direct α‐alkylation reactions of ketones with arylalkenes using an organophotocatalyst and a Brønsted base were developed. It was found that the choice of both Brønsted base and photocatalyst was crucial, and in the presence of catalytic amounts of 2,4,6‐tris(diphenylamino)‐3,5‐difluorobenzonitrile (3DPA2FBN) and LiOtBu, the desired reactions of ketones with styrene analogues proceeded smoothly under blue‐LED light irradiation to afford the products in moderate to high yields. This method constitutes an atom‐economical alkylation process for α‐functionalization of both cyclic and acyclic ketones. [ABSTRACT FROM AUTHOR]