Merging Carbonyl Addition with Photocatalysis DOI
Huan‐Ming Huang, Peter Bellotti, Frank Glorius

et al.

Accounts of Chemical Research, Journal Year: 2022, Volume and Issue: 55(8), P. 1135 - 1147

Published: March 31, 2022

The carbonyl group stands as a fundamental scaffold and plays ubiquitous role in synthetically important chemical reactions both academic industrial contexts. Venerable transformations, including the aldol reaction, Grignard Wittig Nozaki-Hiyama-Kishi constitute vast empowering synthetic arsenal. Notwithstanding, two-electron mechanisms inherently confine breadth of accessible reactivity topological patterns.Fostered by rapid development photoredox catalysis, combing well-entrenched addition radicals can harness several unique increasingly sustainable transformations. In particular, unusual carbon-carbon carbon-heteroatom disconnections, which are out reach chemistry, be conceived. To meet this end, novel strategy toward utilization simple compounds intermolecular radical acceptors was developed. reaction is enabled visible-light photoredox-initiated hole catalysis. situ Brønsted acid activation moiety prevents β-scission from occurring. Furthermore, regioselective alkyl obviates use metals, ligands, or additives, thus offering high degree atom economy under mild conditions. On basis same concept work Schindler co-workers, carbonyl-olefin cross-metathesis, induced visible light, has also been achieved, leveraging Prins-elimination sequence.Recently, dual chromium catalysis developed us Kanai, complementary approach to revered reaction. Leveraging intertwined synergy between light metal, radical-to-polar crossover transformations eminent molecular motifs have Reactions such redox-neutral allylation aldehydes alkylation harvest power enable catalytic metal. Overall, exquisite levels diastereoselectivity enforced via highly compact transition states. Other examples, dialkylation 1,3-dienes propargylation portray versatile combination multicomponent coupling endeavors. Highly valuable motifs, commonly occur complex drug natural product architectures, now accessed single operational step. Going beyond addition, seminal contributions Fagnoni MacMillan preconized photocatalytic HAT-based acyl formation key aldehyde valorization strategy. Our articulated concept, carboxy hydrogen abstractors regio- chemoselective alkynylation trifluoromethylthiolation.This Account, narrative our others' at interface radical-based photochemistry, aims provide core guiding foundations disruptive developments. We envisage that extending crossovers manifolds, taming less-activated carbonyls, processes, merging electron steps with energy-transfer events will propel breakthroughs near future.

Language: Английский

The Persistent Radical Effect in Organic Synthesis DOI
Dirk Leifert, Armido Studer

Angewandte Chemie International Edition, Journal Year: 2019, Volume and Issue: 59(1), P. 74 - 108

Published: May 22, 2019

Abstract Radical–radical couplings are mostly nearly diffusion‐controlled processes. Therefore, the selective cross‐coupling of two different radicals is challenging and not a synthetically valuable transformation. However, if have lifetimes they generated at equal rates, will become dominant process. This high cross‐selectivity based on kinetic phenomenon called persistent radical effect (PRE). In this Review, an explanation PRE supported by simulations simple model systems provided. Radical stabilities discussed within context their lifetimes, various examples PRE‐mediated radical–radical in synthesis summarized. It shown that restricted to coupling with transient radical. If one partner longer‐lived than other radical, operates achieved. important point expands scope chemistry. The Review divided into parts, namely 1) or organic 2) “radical–metal crossover reactions”; here, metal‐centered species more generally transition‐metal complexes able react discussed—a field has flourished recently.

Language: Английский

Citations

652
Catalytic hydrogen atom transfer to alkenes: a roadmap for metal hydrides and radicals DOI Creative Commons
Sophia L. Shevick,

Conner V. Wilson,

Simona Kotesova

et al.

Chemical Science, Journal Year: 2020, Volume and Issue: 11(46), P. 12401 - 12422

Published: Jan. 1, 2020

Hydrogen atom transfer from metal hydrides to alkenes appears underlie widely used catalytic methods – the mechanistic implications are fascinating.

Language: Английский

Citations

266
Reductive radical-polar crossover: traditional electrophiles in modern radical reactions DOI Creative Commons

Lena Pitzer,

J. Luca Schwarz,

Frank Glorius

et al.

Chemical Science, Journal Year: 2019, Volume and Issue: 10(36), P. 8285 - 8291

Published: Jan. 1, 2019

The concept of reductive radical-polar crossover (RRPCO) reactions has recently emerged as a valuable and powerful tool to overcome limitations both radical traditional polar chemistry.

Language: Английский

Citations

250
A Radical Approach to Anionic Chemistry: Synthesis of Ketones, Alcohols, and Amines DOI
Shengyang Ni, Natalia M. Padial, Cian Kingston

et al.

Journal of the American Chemical Society, Journal Year: 2019, Volume and Issue: 141(16), P. 6726 - 6739

Published: April 3, 2019

Historically accessed through two-electron, anionic chemistry, ketones, alcohols, and amines are of foundational importance to the practice organic synthesis. After placing this work in proper historical context, Article reports development, full scope, a mechanistic picture for strikingly different way forging such functional groups. Thus, carboxylic acids, once converted redox-active esters (RAEs), can be utilized as formally nucleophilic coupling partners with other derivatives (to produce ketones), imines benzylic amines), or aldehydes alcohols). The reactions uniformly mild, operationally simple, and, case ketone synthesis, broad scope (including several applications simplification synthetic problems parallel synthesis). Finally, an extensive study synthesis is performed trace elementary steps catalytic cycle provide end-user clear understandable rationale selectivity, role additives, underlying driving forces involved.

Language: Английский

Citations

207
Hydroalkylation of Olefins To Form Quaternary Carbons DOI

Samantha A. Green,

Tucker R. Huffman, Ruairí O. McCourt

et al.

Journal of the American Chemical Society, Journal Year: 2019, Volume and Issue: 141(19), P. 7709 - 7714

Published: April 29, 2019

Metal-hydride hydrogen atom transfer (MHAT) functionalizes alkenes with predictable branched (Markovnikov) selectivity. The breadth of these transformations has been confined to π-radical traps; no sp3 electrophiles have reported. Here we describe a Mn/Ni dual catalytic system that hydroalkylates unactivated olefins alkyl halides, yielding aliphatic quaternary carbons.

Language: Английский

Citations

165
Dialkylation of 1,3-Dienes by Dual Photoredox and Chromium Catalysis DOI

J. Luca Schwarz,

Huan‐Ming Huang,

Tiffany O. Paulisch

et al.

ACS Catalysis, Journal Year: 2019, Volume and Issue: 10(2), P. 1621 - 1627

Published: Dec. 18, 2019

The direct conversion of feedstock chemicals into value-added products is broad interest in chemical research. Herein, we present a regioselective and diastereoselective three-component dialkylation 1,3-dienes with Hantzsch esters aldehydes for the synthesis homoallylic alcohols. reaction enabled by dual photoredox chromium catalysis can also be performed enantioselectively employing chromium-bisoxazoline complexes.

Language: Английский

Citations

155
From Hydrogenation to Transfer Hydrogenation to Hydrogen Auto-Transfer in Enantioselective Metal-Catalyzed Carbonyl Reductive Coupling: Past, Present, and Future DOI
Catherine G. Santana, Michael J. Krische

ACS Catalysis, Journal Year: 2021, Volume and Issue: 11(9), P. 5572 - 5585

Published: April 22, 2021

Atom-efficient processes that occur via addition, redistribution or removal of hydrogen underlie many large volume industrial and pervade all segments chemical industry. Although carbonyl addition is one the oldest most broadly utilized methods for C-C bond formation, delivery non-stabilized carbanions to compounds has relied on premetalated reagents metallic/organometallic reductants, which pose issues safety challenges vis-à-vis implementation. Catalytic reductive couplings promoted hydrogenation, transfer hydrogenation auto-transfer allow abundant unsaturated hydrocarbons serve as substitutes organometallic reagents, enabling formation in absence stoichiometric metals. This perspective (a) highlights past milestones catalytic auto-transfer, (b) summarizes current enantioselective couplings, (c) describes future opportunities based patterns reactivity animate transformations this type.

Language: Английский

Citations

108
A Triple Photoredox/Cobalt/Brønsted Acid Catalysis Enabling Markovnikov Hydroalkoxylation of Unactivated Alkenes DOI

Masanari Nakagawa,

Yuki Matsuki,

Kazunori Nagao

et al.

Journal of the American Chemical Society, Journal Year: 2022, Volume and Issue: 144(18), P. 7953 - 7959

Published: April 27, 2022

We demonstrate Markovnikov hydroalkoxylation of unactivated alkenes using alcohols through a triple catalysis consisting photoredox, cobalt, and Brønsted acid catalysts under visible light irradiation. The realizes three key elementary steps in single catalytic cycle: (1) Co(III) hydride generation by photochemical reduction Co(II) followed protonation, (2) metal hydrogen atom transfer (MHAT) hydride, (3) oxidation the alkyl complex to Co(IV). precise control protons electrons allows elimination strong acids external reductants/oxidants that are required conventional methods.

Language: Английский

Citations

85
A General and Modular Approach to BCP Alkylamines via Multicomponent Difunctionalization of [1.1.1]Propellane DOI
Weichen Huang, Yongxiang Zheng, Sebastian Keeß

et al.

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(9), P. 5363 - 5369

Published: Feb. 21, 2023

Over the past decade, bicyclo[1.1.1]pentane (BCP) motifs have come to fore as valuable pharmaceutical bioisosteres of para-disubstituted benzenes. However, limited approaches and requisite multistep syntheses useful BCP building blocks are hampering early discovery research in medicinal chemistry. Herein we report development a modular strategy for divergent preparation functionalized alkylamines. In this process, general method introduce fluoroalkyl groups scaffolds using readily available easy-to-handle sulfinate salts was also developed. Moreover, can be extended S-centered radicals incorporation sulfones thioethers into core. Overall, multicomponent enables rapid construction BCP-type applications drug discovery.

Language: Английский

Citations

59
Alkene Hydrobenzylation by a Single Catalyst That Mediates Iterative Outer-Sphere Steps DOI

Lingran Kong,

Xu-cheng Gan, Vincent A. van der Puyl

et al.

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(4), P. 2351 - 2357

Published: Jan. 17, 2024

Cross-coupling catalysts typically react and unite functionally distinct partners via sequential inner-sphere elementary steps: coordination, migratory insertion, reductive elimination, etc. Here, we report a single catalyst that cross-couples styrenes benzyl bromides iterative outer-sphere metal–ligand-carbon interactions. Each partner forms stabilized radical intermediate, yet heterocoupled products predominate. The system is redox-neutral and, thus, avoids exogenous oxidants, resulting in simple scalable conditions. Numerous variations of alkene hydrobenzylation are made possible, including access to the privileged heterodibenzyl (1,2-diarylethane) motif challenging quaternary carbon variants.

Language: Английский

Citations

20