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.
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.
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.
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.
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.
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