Enantioselective Reductive Cross‐Coupling of Aryl/Alkenyl Bromides with Benzylic Chlorides via Photoredox/Biimidazoline Nickel Dual Catalysis

Abstract

The asymmetric reductive arylation and alkenylation of benzylic chloride under photoredox/nickel dual catalysis using chiral biimidazoline (BiIm) ligand is reported to access 1,1-diaryl alkanes and aryl allylic compounds with good yield as well as stereo-and enantioselectivities. This protocol uses more commercially available and less expensive C(sp 2 )-Br as the electrophile coupling partner. A primary result using alkenyl chloride and alkyl chloride is also reported. Various functional groups are tolerated and the applications of this method are investigated by late-stage functionalization and gram-scale reaction.

Dual Nickel- and Photoredox-Catalyzed Asymmetric Reductive Cross-Couplings: Just a Change of the Reduction System?

“…In 2022, the Lu and Mao groups respectively reported the asymmetric carbon–carbon formation between benzylic chlorides and aryl/alkenyl bromides under dual Ni/photoredox-catalyzed RCC system with a bis­(oxazole) or biimidazole ligand. Very recently, the Shen group reported an asymmetric arylation of α-bromobenzoates under the dual Ni/photoredox catalysis pattern .…”

Formal Deoxygenative Cross‐Coupling of Aldehydes to Ketones through α‐Haloboronates: A Route to Deoxygenative Hydroacylation of Aldehydes†

“…[ 8 ] However, traditional methods usually rely on the utilization of well‐prepared or in‐situ formed diazocarbonyls, as well as harsh conditions (Figure 1A). [ 9 ] To expand the application of our DODC in organic synthesis, we wondered if the cross‐coupling [ 10 ] of aldehydes and the aforementioned haloboration products would offer an ideal protocol to achieve this target (Figure 1B). The sp 2 ‐hybridized acyl radical can be obtained via the hydrogen‐ atom‐transfer (HAT) process from aldehydes with tetrabutylammonium decatungstate (TBADT) as the photocatalyst; [ 11 ] subsequently, under the nickel catalysis system, α‐boronated ketones would be formed, which are very easy to eliminate in the presence of proton source to give the ketone products according to our previous works.…”

Nickel/Photoredox-Catalyzed Enantioselective Reductive Cross-Coupling between Vinyl Bromides and Benzyl Chlorides

“…Most commonly, organic reductant tetrakis­( N , N -dimethylamino)­ethylene (TDAE) was employed as a reductant for homo-coupling of aryl halides by Tanaka . Subsequently, TDAE was demonstrated to supply electrons in asymmetric reductive cross-electrophile couplings by Reisman, Nevado, and their co-workers (Scheme b). Another strategy reported by Reisman, Mei, and their groups was an enantioselective electroreductive cross-coupling using anodic metal as reductants (Scheme c).…”

“…Hence, we reported here a nickel/photoredox co-catalyzed enantioselective cross-coupling between benzyl and vinyl electrophiles, circumventing the issues encountered when using stoichiometric metal reductants (Scheme c). As a valuable alternative, Lu , and Huo reported nickel/photoredox-catalyzed enantioselective benzylic C­(sp 3 )–H bond alkenylations, respectively. However, their iridium photocatalysts easily reduced E / Z isomerizations of the product via energy transfer pathway under the irradiation of visible light.…”