Exploration of a Chiral Cobalt Catalyst for Visible‐Light‐Induced Enantioselective Radical Conjugate Addition

Abstract

Chiral catalysts tolerating photochemical reactions are in great demand for the vast development of visible-lightinduced asymmetric synthesis.N ow,c hiral octahedral complexes based on earth-abundant metal and chiral N 4 ligands are reported. One well-defined chiral Co II -complex is shown to be an efficient catalyst in the visible-light-induced conjugated addition of enones by alkyl and acyl radicals,p roviding synthetically valued chiral ketones and 1,4-dicarbonyls in 47-> 99 %yields with up to 97:3 e.r.Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.

Cobalt-catalyzed asymmetric phospha-Michael reaction of diarylphosphine oxides for the synthesis of chiral organophosphorus compounds

“…On the basis of some related literature reports 12,13 and our control experiment results, a plausible mechanism is suggested in Fig. 2.…”

“…In 2019, we reported a visible-light-induced cobalt-catalyzed enantioselective radical conjugate addition when the novel chiral Co-centered octahedral complex was used as the catalyst and an imidazolyl moiety as the coordinating group in the Michael acceptors (Scheme 1b). 13 Based on our continuing interest in the synthesis of biologically active organophosphorus compounds, 14 herein, we report a cobalt-catalyzed asymmetric phospha-Michael-type reaction of diarylphosphine oxides with electron-deficient alkenes by introducing an imidazolyl moiety to coordinate with the cobalt complex catalyst in a bidentate chelating form in order to obtain a high enantioselectivity control (Scheme 1c).…”

“…1 Comparison of the stereochemical parameters of ΛCo9 and ΛCo10 with ΛCo2 (CCDC 1870638). 13 Table 2 Substrate scope of the cobalt-catalyzed asymmetric conjugate addition reactions a,b,c a Unless noted otherwise, all reactions were performed with 1 (0.20 mmol), 2 (0.30 mmol, 1.5 equiv. ), CoCl 2 •6H 2 O (0.016 mmol, 8 mol%), L6 (0.018 mmol, 8.6 mol%), AgClO 4 (0.032 mmol, 16 mol%) in dichloromethane (2.0 mL) at room temperature for 48 h. b Isolated yield.…”

Photocatalytic three-component asymmetric sulfonylation via direct C(sp3)-H functionalization

“…The radical ( D ) is rapidly trapped by the sulfur dioxide released in situ to produce the stabilized sulfonyl radical ( E ) 41 . Owing to the electronic and steric effects, E reacts with the metal-coordinated Michael acceptor ( A ) through an outer-sphere rather than an inner-sphere pathway, affording the radical complex ( F ) 60 , 62 – 66 . Such an outer-sphere attack might be critical to avoid side reactions such as self-coupling or elimination and to achieve a high level of asymmetric induction in the photochemical reaction 67 – 80 .…”

Photoredox Catalysis Unlocks the Nickel-Catalyzed Cyanation of Aryl Halides under Benign Conditions

“…With nickel catalysis as an example, the easy formation of Ni(0)-and Ni(II)-cyano complexes were found to hamper the Page 2 of 21 CCS Chemistry elementary oxidative addition and reductive elimination processes in the catalytic cycle, as well as the formation of the Ni(0) catalyst from the Ni(II) precursor [27][28][29] . Over the past decade, dual photoredox/ organometallic catalysis has been established as an important platform for cross-coupling reactions [30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45] .…”