Chromium-Catalyzed Allylic Defluorinative Ketyl Olefin Coupling

Journal of the American Chemical Society, Journal Year: 2021, Volume and Issue: 143(30), P. 11602 - 11610

Published: July 22, 2021

Herein we report a chromium-catalyzed allylic defluorinative ketyl olefin coupling between aldehydes and α-trifluoromethyl alkenes, which provides novel efficient access to diverse gem-difluorohomoallylic alcohols. Remarkably, the high chemoselectivity of this reaction enables conversion formyl moiety in presence various easily reducible functionalities including ketone, organohalides, aziridine, sulfone, alkyne, unactivated alkene. The utility method is demonstrated by simple derivatizations attached hydroxyl group products. preliminary mechanistic investigations suggest pathway with rate-limiting C–C forming step followed facile β-fluoro elimination.

Language: Английский

---

Photoredox/Cr-catalyzed enantioselective radical-polar crossover transformation via C-H functionalization

Nature Communications, Journal Year: 2025, Volume and Issue: 16(1)

Published: Feb. 4, 2025

Asymmetric multicomponent reactions that aim to control multiple chiral centers with high selectivity in a single step remain an on-gonging challenge. The realm of enantioselective radical-polar crossover transformation achieved through C-H Functionalization has yet be fully explored. Herein, we present successful description photoredox/Cr-catalyzed three-component (hetero)arylalkylation 1,3-dienes functionalization. A diverse array homoallylic alcohols could obtained good excellent yields, accompanied by outstanding enantioselectivity. asymmetric build two simultaneously and demonstrates broad substrate tolerance, accommodating various drug-derived aldehydes, (hetero)aromatics, 1,3-diene derivatives. Preliminary mechanistic studies indicate the involvement radical intermediate, allylic chromium species reacting aliphatic aromatic aldehydes Zimmerman–Traxler transition states enabled dual photoredox catalysis. ongoing Here, authors photoredox- chromium-catalyzed

Language: Английский

---

Chromium-catalyzed stereodivergent E- and Z-selective alkyne hydrogenation controlled by cyclic (alkyl)(amino)carbene ligands

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

Published: Feb. 22, 2023

Abstract The hydrogenation of alkynes allows the synthesis olefins, which are important feedstock for materials, pharmaceutical, and petrochemical industry. Thus, methods that enable this transformation via low-cost metal catalysis desirable. However, achieving stereochemical control in reaction is a long-standing challenge. Here, we report on chromium-catalyzed E - Z -selective olefin alkynes, controlled by two carbene ligands. A cyclic (alkyl)(amino)carbene ligand contains phosphino anchor enables trans -addition manner, selectively forming -olefins. With an imino anchor-incorporated ligand, stereoselectivity can be switched, giving mainly -isomers. This ligand-enabled geometrical stereoinversion strategy one overrides common -selectivity with different catalysis, allowing highly efficient on-demand access to both -olefins stereo-complementary fashion. Mechanistic studies indicate steric effect between these ligands may dominate selective or stereochemistry.

Language: Английский

---

Chemoselective 1,2‐Reduction and Regiodivergent Deuteration of Chromium‐Bound Arenes

Angewandte Chemie International Edition, Journal Year: 2023, Volume and Issue: 62(18)

Published: Feb. 23, 2023

Herein, a general strategy for chemo- and regioselective 1,2-reduction of chromium-bound arenes was developed, thus providing rapid access to 1,3-cyclohexadienes. Selective arene activation via π-complexation along with the use mild hydride Ph3 SiH can overcome inherently low reactivity π-bonds while tolerating various reduction-sensitive functional groups. Its versatility further enables regiodivergent deuteration. Using different sequences (non)deuterated acid reagents, deuterated positions as well degrees deuterium incorporation be controlled precisely, which leads large previously inaccessible chemical space 1,3-cyclohexadiene isotopologues. A reasonable mechanism proposed based on intermediate capture control experiments. The synthetic value this selective demonstrated in formal total synthesis (±)-galanthamine (±)-lycoramine.

Language: Английский

---

Low-Valent Transition Metalate Anions in Synthesis, Small Molecule Activation, and Catalysis

Chemical Reviews, Journal Year: 2024, Volume and Issue: 124(4), P. 1323 - 1463

Published: Feb. 14, 2024

This review surveys the synthesis and reactivity of low-oxidation state metalate anions d-block elements, with an emphasis on contributions reported between 2006 2022. Although field has a long rich history, chemistry transition been greatly enhanced in last 15 years by application advanced concepts complex ligand design. In recent years, potential highly reactive complexes fields small molecule activation homogeneous catalysis become increasingly evident. Consequently, exciting applications have developed, including catalytic transformations. article intends to guide reader through fascinating world low-valent metalates. The first part describes metalates stabilized assortment frameworks, carbonyls, isocyanides, alkenes polyarenes, phosphines phosphorus heterocycles, amides, redox-active nitrogen-based ligands. Thereby, will be familiarized impact different types physical chemical properties addition, ion-pairing interactions metal–metal bonding may dramatic influence structures reactivities. ramifications these effects are examined separate section. second is devoted toward inorganic molecules such as H2, N2, CO, CO2, P4 related species. It shown that use electron-rich translates into impressive hydrogenation organic reduction CO2. results discussed this illustrate being tapped for challenging processes relevance energy conversion. Therefore, it hoped serve useful resource inspire further developments dynamic research field.

Language: Английский

---

Enantioselective Remote Alkylation Enabled by Metallaphotoredox Catalysis via Selective C–C Bond Cleavage

ACS Catalysis, Journal Year: 2025, Volume and Issue: 15(3), P. 2212 - 2221

Published: Jan. 23, 2025

Despite recent advances in enantioselective radical coupling with strained cyclic rings, asymmetric reactions triggered by unstrained motifs remain rare. Herein, we report a mild and general strategy for activating diverse set of readily available alcohols the remote site-specific allylic alkylation ketones through combination photoredox-mediated proton-coupled electron transfer chiral chromium catalysis. This newly developed dual catalytic system exhibits extensive applicability, operates under conditions, offers straightforward operation, demonstrates tolerance to functional groups. The open-shell has also been applied late-stage modification complex drug natural product derivatives high levels enantioselectivity.

Language: Английский

---

Nickel-Catalyzed Enantioselective Arylative Activation of Aromatic C–O Bond

Journal of the American Chemical Society, Journal Year: 2021, Volume and Issue: 143(44), P. 18380 - 18387

Published: Oct. 27, 2021

The pioneering nickel-catalyzed cross-coupling of C-O electrophiles was unlocked by Wenkert in the 1970s; however, transition-metal-catalyzed asymmetric activation aromatic bonds has never been reported. Herein first enantioselective an bond is demonstrated via catalytic arylative ring-opening diarylfurans. This transformation facilitated nickel catalysis presence chiral N-heterocyclic carbene ligands, and 2-aryl-2'-hydroxy-1,1'-binaphthyl (ArOBIN) skeletons are delivered axially high yields with ee. Moreover, this versatile skeleton can be transformed into various synthetic useful intermediates, catalysts, ligands using CH- OH-based modifiable sites. chemistry features mild conditions good atom economy.

Language: Английский

---

Nickel-Catalyzed Enantioconvergent Transformation of Anisole Derivatives via Cleavage of C–OMe Bond

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(29), P. 15721 - 15728

Published: July 11, 2023

Herein, a protocol for enantioconvergent transformation of anisole derivatives is disclosed via nickel-catalyzed dynamic kinetic asymmetric cross-coupling the C(Ar)–OMe bond. Versatile axially chiral heterobiaryls are successfully assembled. Synthetic transformations demonstrate application potential this method. Mechanistic studies indicate that enantioconvergence might be accessed through ligand-controlled epimerization diastereomeric 5-membered aza-nickelacycle species rather than conventional resolution.

Language: Английский

---

Chromium‐Catalyzed Reductive Cross‐Coupling to Construct C−SS Bonds from Unactivated Alkyl Electrophiles

ChemCatChem, Journal Year: 2024, Volume and Issue: 16(15)

Published: March 15, 2024

Abstract Low‐valent chromium catalysts are cheap and less toxic compared to other transition metal catalysts. Here in, we reported a ligand‐free chromium(III)‐catalyzed manganese reductive cross‐coupling of unactivated alkyl electrophiles, such as sulfonates chlorides, with trisulfide dioxides thiolation agents form carbon−sulfur bonds. The powerful method featured ample substrate scope wide functional group tolerance, constructing large number unsymmetrical disulfides under simple conditions.

Language: Английский

---

CrCl₂-catalyzed α-alkylation of carbonyl compounds via a borrowing hydrogen approach

Organic Chemistry Frontiers, Journal Year: 2024, Volume and Issue: 11(7), P. 1955 - 1962

Published: Jan. 1, 2024

A new and efficient catalytic system for sustainable α-alkylation of carbonyl compounds with alcohols via a borrowing hydrogen strategy is presented.

Language: Английский

---