Asymmetric Radical Cyclopropanation of α,β-Unsaturated Amides with α-Boryl and α-Silyl Dibromomethanes via Cr(II)-Based Metalloradical Catalysis

Journal of the American Chemical Society, Journal Year: 2025, Volume and Issue: 147(9), P. 7282 - 7292

Published: Feb. 20, 2025

Transition-metal-catalyzed asymmetric carbene-transfer reactions represent a powerful strategy for synthesizing chiral cyclopropanes. However, current methods predominantly rely on stabilized carbene-bearing α-π-conjugated groups, restricting access to less carbenes, such as α-silyl and α-boryl carbenes. Herein, we present an unprecedented Cr(II)-based metalloradical system the cyclopropanation of α,β-unsaturated amides with dibromomethanes in presence Mn reducing agent. Employing chromium complex, reaction proceeds under mild conditions, yielding cyclopropanes three contiguous stereocenters high diastereo- enantioselectivities. This method features Cr-catalyzed radical-based stepwise mechanism. The broad substrate scope, encompassing various amides, demonstrates protocol's versatility robustness. Mechanistic insights, supported by experimental computational studies, suggest formation α-Cr(III)-alkyl radical intermediates, delineating pathway distinct from that classical concerted cyclopropanations. approach provides tool highly functionalized cyclopropanes, offering potential applications drug discovery development.

Language: Английский

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Late‐Stage Diazoester Installation via Arylthianthrenium Salts

Angewandte Chemie International Edition, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 7, 2025

Abstract By leveraging the fast oxidative addition of arylthianthrenium salts (aryl‐TT + ) to palladium(0), a regioselective diazoester installation has been developed. This approach enables introduction diazo moiety densely functionalized arenes at late stage. The installed group is amenable facile further derivatization.

Language: Английский

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Late‐Stage Diazoester Installation via Arylthianthrenium Salts

Angewandte Chemie, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 7, 2025

Abstract By leveraging the fast oxidative addition of arylthianthrenium salts (aryl‐TT + ) to palladium(0), a regioselective diazoester installation has been developed. This approach enables introduction diazo moiety densely functionalized arenes at late stage. The installed group is amenable facile further derivatization.

Language: Английский

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Flow Electroreductive Nickel‐Catalyzed Cyclopropanation of Alkenes Using gem‐Dichloroalkanes

Angewandte Chemie International Edition, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 31, 2025

Abstract Cyclopropanes are valuable motifs in organic synthesis, widely featured pharmaceuticals and functional materials. Herein, we report an efficient electrochemical methodology for the cyclopropanation of alkenes, leveraging a nickel‐catalyzed process continuous‐flow. The developed protocol demonstrates broad substrate scope, accommodating both electron‐rich electron‐poor alkenes with high group tolerance. Beyond dichloromethane as feedstock methylene source, enables synthesis methylated, deuterated, chloro‐substituted cyclopropanes. Mechanistic investigations suggest electro‐generation nickel carbene key intermediate. Notably, reaction operates under ambient conditions, tolerates air moisture, achieves scalability through continuous‐flow technology, offering straightforward route to multi‐gram quantities enhanced throughput.

Language: Английский

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Carbenoid Reactions Promoted by Solids: From Lewis to Brønsted Catalysts

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

Published: April 23, 2025

ConspectusDiazocarbonyl compounds have become essential tools in organic synthesis, due to their ability situ generate reactive carbenes and be inserted a variety of otherwise stable bonds, such as C-H, C-C, H-O, so on. However, soluble metal salt or complex catalyst is generally required selectively activate couple the carbene, metals employed far are expensive (Rh, Au, Ag, Cu) often unrecoverable. It noteworthy that price ligands can make cheaper (i.e., other ligand-free noble catalysts. In realm modern sustainable chemistry, most these methodologies now unacceptable must adapted, simple strategies for include carbene photoactivation use recoverable solid Unfortunately, despite research field insertion reactions has extended more than 50 years, examples with catalysts still minor, efficient only been reported last two decades.This Account shows journey faced by our group eight years find challenging reactions, employing diazocarbonyl precursors. We will contextualize results those previous The discovery 2017 quasi-linear Pd4 cluster stabilized within metal-organic framework (MOF) was able catalyze Büchner spurred design supported clusters reactions. Pd4-MOF could reused 20 times batch implemented flow process. Following this, catalytic solids, including Au Ag metals, not same MOF but also on oxides zeolites supports, showed good activity were reusable.Our temporarily finishes 2024 when "blank" experiments dealuminated zeolite surprisingly revealed this acid, without any metal, easily activates compound catalyzes thus providing cheap, commercially available, reusable Overall, rapid progress solid-catalyzed activation, formation, achieved during moving from difficult prepare based acid zeolites, pointing confined Brønsted acids study near future.

Language: Английский

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Homologation of Alkenyl Carbonyls via a Cyclopropanation/Light‐Mediated Selective C‐C Cleavage Strategy

Angewandte Chemie International Edition, Journal Year: 2024, Volume and Issue: unknown

Published: Oct. 31, 2024

We report herein our studies on the direct photoactivation of carbonyl cyclopropanes to give biradical intermediates, leading selective cleavage more substituted carbon-carbon bond. Depending substrate structure, extended alkenes were isolated or directly reacted in a photo-Nazarov process bicyclic products. Based these results, unified reductive ring-opening reaction was developed by using diphenyl disulfide as hydrogen atom transfer (HAT) reagent. By performing sequential cyclopropanation/selective ring opening reaction, we achieved CH

Language: Английский

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Homologation of Alkenyl Carbonyls via a Cyclopropanation/Light‐Mediated Selective C‐C Cleavage Strategy

Angewandte Chemie, Journal Year: 2024, Volume and Issue: unknown

Published: Oct. 31, 2024

Abstract We report herein our studies on the direct photoactivation of carbonyl cyclopropanes to give biradical intermediates, leading selective cleavage more substituted carbon‐carbon bond. Depending substrate structure, extended alkenes were isolated or directly reacted in a photo‐Nazarov process bicyclic products. Based these results, unified reductive ring‐opening reaction was developed by using diphenyl disulfide as hydrogen atom transfer (HAT) reagent. By performing sequential cyclopropanation/selective ring opening reaction, we achieved CH 2 insertion into α,β bond both acyclic and cyclic unsaturated compounds. Our protocol provides further tool for modification carbon framework organic compounds, complementing recent progress “skeletal editing”.

Language: Английский

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