Copper-Catalyzed Asymmetric Acylboration of 1,3-Butadienylboronate with Acyl Fluorides

Enantioselective Ni-Catalyzed 1,2-Borylalkynylation of Unactivated Alkenes

Enantioselective three-component difunctionalization of alkenes with boron reagents represents an attractive strategy for assembling three-dimensional chiral organoboron compounds. However, regio- and enantiocontrol comprise the pivot challenges in these transformations, which predominantly require the use of activated conjugated alkenes. Herein, by utilizing various carbonyl directing groups, including amides, sulfinamides, ketones, and esters, we succeed in realizing a nickel-catalyzed 1,2-borylalkynylation of unactivated alkenes to enable the simultaneous incorporation of a boron entity and an sp-fragment across the double bond. The products contain boryl, alkynyl, and carbonyl functional groups with orthogonal synthetic reactivities, offering three handles for further derivatization to access valuable intermediates. The utility of this ligand-enabled asymmetric protocol has been highlighted through the late-stage decoration of drug-relevant molecules.

Enantio- and Regioselective Cascade Hydroboration of Methylenecyclopropanes for Facile Access to Chiral 1,3- and 1,4-Bis(boronates)

Chiral 1, n-bis(boronate) plays a crucial role in organic synthesis and medicinal chemistry. However, their catalytic and asymmetric synthesis has long posed a challenge in terms of operability and accessibility from readily available substrates. The recent discovery of the C═C bond formation through β-C elimination of methylenecyclopropanes (MCP) has provided an exciting opportunity to enhance molecular complexity. In this study, the catalyzed asymmetric cascade hydroboration of MCP is developed. By employing different ligands, various homoallylic boronate intermediate are obtained through the hydroboration ring opening process. Subsequently, the cascade hydroboration with HBpin or B2pin2 resulted in the synthesis of enantioenriched chiral 1,3- and 1,4-bis(boronates) in high yields, accompanied by excellent chemo- and enantioselectivities. The selective transformation of these two distinct C─B bonds also demonstrated their application potential in organic synthesis.

Palladium-Catalyzed Atroposelective Suzuki-Miyaura Coupling to Construct Axially Chiral Tetra-Substituted α-Boryl Styrenes

Palladium-catalyzed Suzuki-Miyaura (SM) coupling is a valuable method for forming C─C bonds, including those between aryl moieties. However, achieving atroposelective synthesis of axially chiral styrenes via SM coupling remains challenging. In this study, a palladium-catalyzed atroposelective Suzuki-Miyaura coupling between gem-diborylalkenes and aryl halides is presented. Using the monophosphine ligand Me-BI-DIME (L2), a range of axially chiral tetra-substituted acyclic styrenes with high yields and excellent enantioselectivities are successfully synthesized. Control experiments reveal that the gem-diboryl group significantly influences the product enantioselectivities and the coupling prefers to occur at sites with lower steric hindrance. Additionally, the alkenyl boronate group in the products proves versatile, allowing for various transformations while maintaining high optical purities.

Cooperative Cu/Pd-Catalyzed 1,5-Boroacylation of Cyclopropyl-Substituted Alkylidenecyclopropanes

A Cu/Pd-cocatalyzed 1,5-boroacylation of cyclopropyl-substituted ACPs with B2pin2 and acid chlorides has been developed. Using cyclopropyl-substituted ACPs as the starting material, a broad range of 1,5-boroacylated products with multiple functional groups was prepared in good yields with excellent regio- and stereoselectively. Both aromatic and aliphatic acid chlorides were tolerated in this reaction.

Cu-Catalyzed Asymmetric Dicarboxylation of 1,3-Dienes with CO2

Dicarboxylic acids and derivatives are important building blocks in organic synthesis, biochemistry, and the polymer industry. Although catalytic dicarboxylation with CO2 represents a straightforward and sustainable route to dicarboxylic acids, it is still highly challenging and limited to generation of achiral or racemic dicarboxylic acids. To date, catalytic asymmetric dicarboxylation with CO2 to give chiral dicarboxylic acids has not been reported. Herein, we report the first asymmetric dicarboxylation of 1,3-dienes with CO2 via Cu catalysis. This strategy provides an efficient and environmentally benign route to chiral dicarboxylic acids with high regio-, chemo-, and enantioselectivities. The copper self-relay catalysis, that is, Cu-catalyzed boracarboxylation of 1,3-dienes to give carboxylated allyl boronic ester intermediates and subsequent carboxylation of C-B bonds to give dicarboxylates, is key to the success of this dicarboxylation. Moreover, this protocol exhibits broad substrate scope, good functional group tolerance, easy product derivatizations, and facile synthesis of chiral liquid crystalline polyester and drug-like scaffolds.