Modular and Fast Synthesis of Versatile Secondary α,α-Dialkyl Boronates via Deoxygenative Alkylboration of Aldehydes.

Secondary α,α-dialkyl boronates are widely used due to their great versatility. Herein we report an unprecedented deoxygenative alkylboration of aldehydes, a facile method to access this type of products. A sequence of difunctionalization can be obtained smoothly from the readily available aldehydes in only two steps. This difunctionalization of aldehydes rather than conventional alkenes also opens new possibilities within the field.

Modular and Facile Access to Chiral α-Aryl Phosphates via Dual Nickel- and Photoredox-Catalyzed Reductive Cross-Coupling.

Chiral phosphine-containing skeletons are important motifs in bioactive natural products, pharmaceuticals, chiral catalysts, and ligands. Herein, we report a general and modular platform to access chiral α-aryl phosphorus compounds via a Ni/photoredox-catalyzed enantioconvergent reductive cross-coupling between α-bromophosphates and aryl iodides. This dual catalytic regime exhibited high efficiency and good functional group compacity. A wide variety of substrates bearing a diverse set of functional groups could be converted into chiral phosphates in good to excellent yields and enantioselectivities. The utility of the method was also demonstrated by the development of a new phosphine ligand and the synthesis of enzyme inhibitor derivatives. The detailed mechanistic studies supported a radical chain process and revealed a unique distinction compared with traditional reductive cross-coupling.

Dual Ni/photoredox-catalyzed asymmetric cross-coupling to access chiral benzylic boronic esters.

The flourishing Ni/photoredox-catalyzed asymmetric couplings typically rely on redox-neutral reactions. In this work, we report a reductive cross-coupling of aryl iodides and α-chloroboranes under a dual catalytic regime to further enrich the metallaphotoredox chemistry. This approach proceeds under mild conditions (visible light, ambient temperature, no strong base) to access the versatile benzylic boronic esters with good functional group tolerance and excellent enantioselectivities.

Dual Nickel- and Photoredox-Catalyzed Reductive Cross-Coupling of Aryl Halides with Dichloromethane via a Radical Process.

The first catalytic strategy to harness a new chloromethane radical from dichloromethane under dual Ni/photoredox catalytic conditions has been developed. Compared with traditional two-electron reductive process associated with metallic reductants, this method via a single-electron approach can proceed under exceptionally mild conditions (visible light, ambient temperature, no strong base) and exhibits complementary reactivity patterns. It affords a broad scope of many functional groups, including alkenyl, which suffers cyclopropanation in previous routes. The diarylmethane-d2 compounds can be readily available with this transformation.

Enantioselective Copper-Catalyzed Desymmetrization of 1,3-Diketones Involving Borylation of Styrenes.

A copper-catalyzed intramolecular enantioselective and diastereoselective borylative coupling of styrenes and ketones was achieved by merging desymmetrization strategy and olefin difunctionalization. The reaction proceeds through an initial enantioselective borylcupration of styrenes, followed by a highly selective direct addition to 1,3-diketones. The bicyclic scaffolds with three chiral carbon centers, including two tetrasubstituted carbons, were generated in excellent yields, diastereoselectivities, and enantioselectivities. This catalytic tandem reaction has great potential for further synthetic application of the chiral polycyclic compounds, because of the versatility of the functional groups in the products.

Palladium-Catalyzed Cross-Coupling of gem-Bis(boronates) with Aryl Halides: An Alternative To Access Quaternary α-Aryl Aldehydes.

The compounds with a quaternary α-aryl aldehyde skeleton are important units in organic chemistry. Previously, the aryl group and carbonyl group are introduced in a stepwise manner. Herein, a novel route is developed to construct the quaternary α-aryl aldehydes with gem-bis(boronates) as precursors, in which the two groups are installed simultaneously. The gem-bis(boronates) are readily available from ketones; as a result, this methodology provides a more general strategy to produce the quaternary α-aryl aldehydes with broad scopes and synthetic convenience.

Difunctionalization of ketones via gem-bis(boronates) to synthesize quaternary carbon with high selectivity.

All-carbon quaternary centres are significant and prevalent structural frameworks but their preparation routes are rare and challenging, especially methods with common substrates. Herein, we report a convenient process to construct all-carbon quaternary centres from ketones via the diborylation process and Suzuki-Miyaura cross-coupling reaction. This methodology, which simultaneously introduces two different kinds of electrophilic structures, exhibits a large substrate scope and high functional group tolerance. The reaction products with aldehyde and allylic groups have proved to be versatile synthons to prepare complex molecules crucial for natural product synthesis.