Enantioselective electrochemical cobalt-catalyzed aryl C–H activation reactions

Science, Journal Year: 2023, Volume and Issue: 379(6636), P. 1036 - 1042

Published: March 10, 2023

Enantioselective redox transformations typically rely on costly transition metals as catalysts and often stoichiometric amounts of chemical agents well. Electrocatalysis represents a more sustainable alternative, in particular through the use hydrogen evolution reaction (HER) place oxidant. In this work, we describe strategies for HER-coupled enantioselective aryl carbon-hydrogen bond (C-H) activation reactions using cobalt precious metal catalyst asymmetric oxidation. Thus, highly nitrogen-hydrogen (C-H N-H) annulations carboxylic amides were achieved, which gave access to point axially chiral compounds. Furthermore, cobalt-mediated electrocatalysis enabled preparation various phosphorus (P)-stereogenic compounds by selective desymmetrization dehydrogenative C-H reactions.

Language: Английский

---

Enantio‐ and Regioselective Electrooxidative Cobalt‐Catalyzed C−H/N−H Annulation with Alkenes

Angewandte Chemie International Edition, Journal Year: 2023, Volume and Issue: 62(11)

Published: Jan. 20, 2023

In recent years, the merging of electrosynthesis with 3d metal catalyzed C-H activation has emerged as a sustainable and powerful technique in organic synthesis. Despite impressive advantages, development an enantioselective version remains elusive poses daunting challenge. Herein, we report first electrooxidative cobalt-catalyzed enantio- regioselective C-H/N-H annulation olefins using undivided cell at room temperature (up to 99 % ee). t Bu-Salox, rationally designed Salox ligand bearing bulky tert-butyl group ortho-position phenol, was found be crucial for this asymmetric reaction. A strong cooperative effect between Bu-Salox 3,4,5-trichloropyridine enabled highly more challenging α-olefins without secondary bond interactions 96 ee 97 : 3 rr). Cyclovoltametric studies, preparation, characterization, transformation cobaltacycle intermediates shed light on mechanism

Language: Английский

---

Single‐Step Synthesis of Atropisomers with Vicinal C−C and C−N Diaxes by Cobalt‐Catalyzed Atroposelective C−H Annulation

Angewandte Chemie International Edition, Journal Year: 2022, Volume and Issue: 61(39)

Published: Aug. 2, 2022

The atroposelective synthesis of atropisomers with vicinal diaxes remains rare and challenging, due to the steric influence between two axes their unique topology. Herein, we disclose a single-step construction C-C C-N chiral by cyclopentadiene (Cp)-free cobalt-catalyzed intramolecular C-H annulation, providing desired diaxial structures decent stereocontrols both (up >99 % ee 70 : 1 dr). optically pure products bearing fluorophores show circular polarized luminescence (CPL) properties, being candidate materials for potential CPL applications. Atropisomerization experiments density function theory (DFT) calculations are conducted study rotational barriers rotation pathways diaxes.

Language: Английский

---

Base‐Promoted Electrochemical Co^II‐catalyzed Enantioselective C−H Oxygenation

Angewandte Chemie International Edition, Journal Year: 2023, Volume and Issue: 62(21)

Published: March 20, 2023

Metalla-electrocatalyzed C-H oxygenation represents one of the most straightforward and sustainable approaches to access valuable oxygenated molecules. Despite significant advances, development enantioselective electrochemical reaction is very challenging remains elusive. Herein, we described first CoII -catalyzed alkoxylation. A broad range enantioenriched alkoxylated phosphinamides were obtained in good yields with excellent enantioselectivities (up 98 % yield >99 ee). An unusual cobalt(III) alcohol complex was prepared fully characterized, which proven be a key intermediate this alkoxylation reaction. Mechanistic studies revealed that oxidation CoIII CoIV facilitated by base whole process proceeded through cobalt(III/IV/II) catalytic cycle.

Language: Английский

---

Cobalt-catalyzed atroposelective C−H activation/annulation to access N−N axially chiral frameworks

Nature Communications, Journal Year: 2023, Volume and Issue: 14(1)

Published: Aug. 29, 2023

The N-N atropisomer, as an important and intriguing chiral system, was widely present in natural products, pharmaceutical lead compounds, advanced material skeletons. anisotropic structural characteristics caused by its special axial rotation have always been one of the challenges that chemists strive to overcome. Herein, we report efficient method for enantioselective synthesis axially frameworks via a cobalt-catalyzed atroposelective C-H activation/annulation process. reaction proceeds under mild conditions using Co(OAc)2·4H2O catalyst with salicyl-oxazoline (Salox) ligand O2 oxidant, affording variety products high yields enantioselectivities. This protocol provides approach facile construction atropisomers further expands range derivatives. Additionally, electrocatalysis, desired were also successfully achieved good excellent efficiencies

Language: Английский

---

Cobalt-Catalyzed Enantioselective C–H Annulation with Alkenes

ACS Catalysis, Journal Year: 2023, Volume and Issue: 13(7), P. 4250 - 4260

Published: March 13, 2023

Herein, we disclose an efficient cobalt-catalyzed enantioselective C–H activation and annulation of benzamides with alkenes. This transformation is facilitated via the commercially available cobalt(II) catalyst in presence easily prepared chiral salicyl-oxazoline (Salox) ligand, which provides facile access to (R) or (S) enantiomers dihydroisoquinolone derivatives. It noticeable that reaction proceeded efficiently within extremely short time from 10 30 min under mild conditions. A broad range alkenes bear various functional substituents have been shown good compatibility deliver targeted products high yields enantioselectivities (51 examples, up 98% yield 99% ee). The gram scale experiment removal directing group further demonstrate practicability this protocol potential industrial applications. Density theory calculations elucidate mechanism, spin-state change olefin insertion step accelerates subsequent C–N reductive elimination, identified as stereo-determining step. AIM analysis indicates π interactions are vital for controlling switching stereoselectivity.

Language: Английский

---

Cobalt‐Catalyzed Enantioselective C−H Carbonylation towards Chiral Isoindolinones

Angewandte Chemie International Edition, Journal Year: 2024, Volume and Issue: 63(10)

Published: Jan. 11, 2024

Transition metal-catalyzed enantioselective C-H carbonylation with carbon monoxide, an essential and easily available C1 feedstock, remains challenging. Here, we disclosed unprecedented catalyzed by inexpensive readily cobalt(II) salt. The reactions proceed efficiently through desymmetrization, kinetic resolution, parallel affording a broad range of chiral isoindolinones in good yields excellent enantioselectivities (up to 92 % yield 99 ee). synthetic potential this method was demonstrated asymmetric synthesis biological active compounds, such as (S)-PD172938 (S)-Pazinaclone. resulting also serve ligands cobalt-catalyzed annulation alkynes construct phosphorus stereocenter.

Language: Английский

---

Second Generation Catalytic Enantioselective Nucleophilic Desymmetrization at Phosphorus (V): Improved Generality, Efficiency and Modularity

Angewandte Chemie International Edition, Journal Year: 2024, Volume and Issue: 63(18)

Published: Feb. 21, 2024

A broadly improved second generation catalytic two-phase strategy for the enantioselective synthesis of stereogenic at phosphorus (V) compounds is described. This protocol, consisting a bifunctional iminophosphorane (BIMP) catalyzed nucleophilic desymmetrization prochiral, bench stable P(V) precursors and subsequent enantiospecific substitution allows divergent access to wide range C-, N-, O- S- substituted containing from handful enantioenriched intermediates. new ureidopeptide BIMP catalyst/thiaziolidinone leaving group combination allowed far wider substrate scope increased reaction efficiency practicality over previously established protocols. The resulting intermediates could then be transformed into an even greater distinct classes by displacement remaining as well allowing further diversification downstream. Density functional theory (DFT) calculations were performed pinpoint origin enantioselectivity BIMP-catalyzed desymmetrization, rationalize how superior catalyst/leaving leads generality in our second-generation system, shed light onto observed stereochemical retention inversion pathways when performing late-stage S

Language: Английский

---

Cobalt(III)-Catalyzed Enantioselective C–H Functionalization: Ligand Innovation and Reaction Development

Accounts of Chemical Research, Journal Year: 2025, Volume and Issue: unknown

Published: Feb. 26, 2025

ConspectusIn contrast to precious transition metals, such as palladium and rhodium, the development of novel chiral ligands for enantioselective C-H functionalizations catalyzed by earth-abundant, cost-effective, environmentally friendly 3d metals poses substantial challenges, primarily due variable oxidation states, intricate coordination patterns, limited mechanistic insights. In this Account, we summarize our research endeavors in three types Co(III) catalysis: pseudotetrahedral achiral Cp*Co(III)/chiral carbonyl acid (CCA) catalysis, situ-generated octahedral cobalt(III) via cobalt/salicyloxazoline (Salox) Co(II)/chiral phosphoric (CPA) cooperative achieved through strategic ligand design. Our initial objective was achieve functionalization Cp*Co(III) catalysts with external ligands, aiming circumvent laborious preparation CpxCo(III) complexes. To end, developed several CCA incorporating non-covalent interactions (NCIs) a crucial design element. Next, address limitations associated lengthy synthesis Cp-ligated complexes difficulties modification, explored concept situ generation catalysis using commercially available cobalt(II) salts tailor-made ligands. This exploration led two innovative catalytic systems, namely, Co(II)/Salox Co(II)/CCA sequential catalysis. The emerged versatile strategy, demonstrating excellent enantioselectivities across range asymmetric reactions construct various molecules central, axial, planar, inherent chirality. facile single step, along ease further enhances versatility applicability approach. Moreover, successfully applied cobalt/Salox electro- photochemical-catalyzed functionalization, electrons or oxygen traceless oxidant, thereby eliminating need stoichiometric chemical oxidants. Through studies reaction developments, elucidated detailed structure-enantioselectivity relationships which are expected inform future endeavors. Finally, Co(II)/CPA enabled spiro-γ-lactams olefination/asymmetric [4 + 1] spirocyclization. Mechanistically, establishment stereochemistry occurs during cyclization where CPA serves both neutral Brønsted acid, stereoinduction independent cleavage step. We anticipate that insights advancements Account will inspire innovations drive progress metal-catalyzed reactions.

Language: Английский

---

Cobalt/Salox‐Catalyzed Enantioselective Dehydrogenative C−H Alkoxylation and Amination

Angewandte Chemie International Edition, Journal Year: 2022, Volume and Issue: 61(38)

Published: Aug. 2, 2022

The past decade has witnessed a rapid progress in asymmetric C-H activation. However, the enantioselective alkoxylation and amination with alcohols free amines remains elusive. Herein, we disclose first dehydrogenative enabled by simple cobalt/salicyloxazoline (Salox) catalysis. use of cheap readily available cobalt(II) salts as catalysts Saloxs chiral ligands provides an efficient method to access P-stereogenic compounds excellent enantioselectivities (up >99 % ee). practicality this protocol is demonstrated gram-scale preparation further derivatizations resulting phosphinamides, which offering flexible alternative mono- diphosphine ligands. Preliminary mechanistic studies on reaction suggest that cobalt(III/IV/II) catalytic cycle might be involved.

Language: Английский

---