Copper-catalysed asymmetric reductive cross-coupling of prochiral alkenes

Conjugate Addition of Chiral Allenylcopper Species to Vinyl Bis(sulfone) To Access an All-Carbon Quaternary Center

Asymmetric formation of all-carbon quaternary centers has been recognized as a challenging area in organic synthesis. Herein, we report a copper-catalyzed approach toward coupling of two alkenyl substrates, resulting in the formation of a chiral all-carbon quaternary center. In the reaction, axially chiral tetrasubstituted allenylcopper species were generated catalytically and chemoselectively, in situ from the substituted enynes, and remarkably performed as an efficient organometallic nucleophile in conjugate addition to unsaturated sulfones.

19F NMR-Based Chiral Analysis of Organoboron Compounds via Chiral Recognition of Fluorine-Labeled Boronates with Cobalt Complexes

This study aims to develop a method for the chiral analysis of organoboron compounds using nuclear magnetic resonance (NMR) spectroscopy. It addresses the longstanding challenge associated with these chiral organoboron compounds, which often require derivatization and pretreatment prior to chromatographic analysis. Our method utilizes tridentate ligands to facilitate effective ligand exchange and incorporates fluorine labels, allowing for the precise discrimination of 19F NMR signals. This is achieved in conjunction with a chiral cationic cobalt complex, serving as the chiral solvating agent. This approach provides reliable and rapid determination of enantiomeric excess in a wide range of organoboron compounds, featuring various functional groups, and establishes a universal tool for assessing the optical purity of these substances.

Asymmetric Conjugate Addition of Vinyl Arene-Derived Chiral Benzylcopper Nucleophiles

We report the copper-catalyzed asymmetric conjugate addition of vinyl arene-derived nucleophiles to α,β-unsaturated diesters. Due to the high electrophilicity of α,β-unsaturated diesters toward nucleophilic copper catalysts, inclusion of vinyl arenes as pronucleophiles is challenging due to chemoselectivity issues in a multicomponent reaction compared with those of other successful examples of dienes, allenes, and enynes. In this method, chemoselective in situ generation of a chiral benzylic copper intermediate and its stereoselective addition to α,β-unsaturated diesters provided organoboron adducts with contiguous stereogenic centers with good levels of diastereoselectivity and enantioselectivity (≤85:15 diastereomeric ratio and 99% enantiomeric excess, respectively).

Asymmetric alkene-alkene reductive cross-coupling reaction via visible-light photoredox/cobalt dual catalysis

The first example of asymmetric alkene-alkene reductive coupling is demonstrated via visible-light-fueled photoredox/cobalt dual catalysis. The desymmetrization reaction provided products (>20 examples) with up to five chiral centers in single-step operation in up to 95% yields with very high relative (>99 : 1 dr) and absolute stereochemistry (up to 98 : 2 er) control. The preliminary mechanistic investigations suggested that the critical mechanistic steps involved light-mediated controlled low-valent cobalt complex generation, oxidative ene-ene cyclization, and protonation.

Asymmetric Synthesis of β-Aminoboronates via Copper-Catalyzed Reductive Coupling of Vinyl Boronates with Imines

We report a copper-catalyzed asymmetric reductive coupling of vinyl boronates with imines, which directly access enantiomerically enriched β-aminoalkylboronates. Stereoselective addition of the in situ generated chiral α-borylalkyl copper to N-phosphinoyl imines provided target products in good yields with high diastereo- and enantioselectivity. Vinyl boronate with methylated acenaphthoquinone as a boron ligand was essential to efficiently spawn asymmetric products, and organic transformations of the boron moiety, along with the easily removable N-protecting group, proved their synthetic utility.

The potential of converting carbon dioxide to food compounds via asymmetric catalysis

The food crisis caused by diminished arable land, extreme weather and climate change linked to increased carbon dioxide (CO₂) emission, is threatening global population growth. Interestingly, CO₂, the most widespread carbon source, can be converted into food ingredients. Here, we briefly discuss the progress and challenges in catalytic conversion of CO₂ to food ingredients via chiral catalysis.

Enantioselective and Diastereodivergent Allylation of Propargylic C-H Bonds

An iridium-catalyzed stereoselective coupling of allylic ethers and alkynes to generate 3,4-substituted 1,5-enynes is reported. Under optimized conditions, the coupling products are formed with excellent regio-, diastereo-, and enantioselectivities, and the protocol is functional group tolerant. Moreover, we report conditions that allow the reaction to proceed with complete reversal of diastereoselectivity. Mechanistic studies are consistent with an unprecedented dual role for the iridium catalyst, enabling the propargylic deprotonation of the alkyne through π-coordination, as well as the generation of a π-allyl species from the allylic ether starting material.