The Carbene Chemistry of N-Sulfonyl Hydrazones: The Past, Present, and Future

Chemical Reviews, Год журнала: 2025, Номер unknown

Опубликована: Янв. 10, 2025

N-Sulfonyl hydrazones have been extensively used as operationally safe carbene precursors in modern organic synthesis due to their ready availability, facile functionalization, and environmental benignity. Over the past two decades, there has tremendous progress chemistry of N-sulfonyl presence transition metal catalysts, under metal-free conditions, or using photocatalysts photoirradiation conditions. Many transfer reactions are unique cannot be achieved by any alternative methods. The discovery novel development highly enantioselective new skeletal editing represent notable recent achievements hydrazones. This review describes overall made hydrazones, organized based on reaction types, spotlighting current state-of-the-art remaining challenges addressed future. Special emphasis is devoted identifying, describing, comparing scope limitations methodologies, key mechanistic scenarios, potential applications complex molecules.

Язык: Английский

---

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, Год журнала: 2025, Номер 147(9), С. 7282 - 7292

Опубликована: Фев. 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.

Язык: Английский

---

Asymmetric Three-Component Radical Alkene Carboazidation by Direct Activation of Aliphatic C–H Bonds

Journal of the American Chemical Society, Год журнала: 2024, Номер 146(19), С. 13347 - 13355

Опубликована: Май 6, 2024

Azide compounds are widely present in natural products and drug molecules, their easy-to-transform characteristics make them used the field of organic synthesis. The merging transition-metal catalysis with radical chemistry offers a versatile platform for carboazidation alkenes, allowing rapid assembly highly functionalized azides. However, direct use readily available hydrocarbon feedstocks as sp

Язык: Английский

---

Stereoselective Synthesis of Silyl Enol Ethers with Acylsilanes and α,β-Unsaturated Ketones

Organic Letters, Год журнала: 2024, Номер 26(28), С. 5911 - 5916

Опубликована: Июль 8, 2024

Acylsilanes are emerging bench-stable reagents for the generation of electron-rich oxycarbenes that difficult to access with unstable diazo compounds. Herein, we report a siloxycarbene-mediated stereoselective synthesis silyl enol ethers through visible-light-induced intermolecular reactions between acylsilanes and α,β-unsaturated ketones. Both solvent low temperature important success reaction. This approach features atomic economics, exclusive stereocontrol, broad substrate scope. The synthetic potential this methodology is demonstrated by gram-scale reaction various downstream transformations including requiring configuration purity ethers.

Язык: Английский

---

Nature-Inspired Radical Pyridoxal-Mediated C–C Bond Formation

Journal of the American Chemical Society, Год журнала: 2024, Номер 146(33), С. 23321 - 23329

Опубликована: Авг. 6, 2024

Pyridoxal-5'-phosphate (PLP) and derivatives of this cofactor enable a plethora reactions in both enzyme-mediated free-in-solution transformations. With few exceptions each category, such chemistry has predominantly involved two-electron processes. This sometimes poses significant challenge for using PLP to build tetrasubstituted carbon centers, especially when the reaction is reversible. The ability access radical pathways paramount broadening scope catalyzed by coenzyme. In study, we demonstrate PLP-based intermediate engage number C-C bond-forming reactions. By selection an appropriate oxidant, single-electron oxidation quinonoid can be achieved, which subsequently applied Through pathway, synthesized series α-tertiary amino acids esters investigate substrate identify nonproductive pathways. Beyond acid model system, that other classes amine substrates range small molecule reagents serve as coupling partners semiquinone radical. We anticipate versatile species will central development novel

Язык: Английский

---

Design and Synthesis of C₄‐Symmetric Axially Chiral β‐Aryl Porphyrins and Application for Supporting Ir(III)‐Catalyzed Enantioselective C−H Alkylation

Angewandte Chemie International Edition, Год журнала: 2024, Номер 63(28)

Опубликована: Апрель 29, 2024

A hitherto unknown class of C

Язык: Английский

---

Copper-catalysed synthesis of chiral alkynyl cyclopropanes using enantioconvergent radical cross-coupling of cyclopropyl halides with terminal alkynes

Nature Synthesis, Год журнала: 2024, Номер unknown

Опубликована: Сен. 26, 2024

Язык: Английский

---

Radicals as Chiral Catalysts for Asymmetric Radical Cyclization Reactions

Chinese Journal of Chemistry, Год журнала: 2024, Номер 42(19), С. 2412 - 2416

Опубликована: Май 31, 2024

Abstract Due to the innate highly reactive properties and short life‐time, organic free radicals can often serve as promoters or intermediates engage in various radical transformations, which are otherwise difficult access by ionic pathway‐based mechanisms. With evolvement of chemistry, chiral catalyzed‐transformations have recently emerged an attractive robust platform for synthesis molecules interest. Herein, we highlight several creative strategic advances catalyst design, cyclization reaction achievements, future challenges. Key Scientists In 1980s, some pioneering studies Feldman Oshima revealed that thiyl could catalyze vinylcyclopropane with alkenes, providing racemic cyclopentanes. 1996, Brian P. Roberts reported interesting enantioselective hydrosilylation prochiral alkenes using thioglucose‐derived catalysts. Since then, catalysis has become emerging promising catalytic strategy synthesis. However, this field not been extensively explored further until Maruoka group 2014 achieved asymmetric C—C bond formation employing a newly designed indanol core‐based catalyst. protocol, vinylcyclopropanes electron‐rich was developed. 2020, Chen Xiao disclosed nitrogen radical‐catalyzed version reaction. Later, expanded metalloradical catalyzed cascade reactions Zhang 2021. Later on, Wang, Fu et al . described novel class boryl cycloisomerization reactions, showcasing enormous synthetic potential catalysis. This Emerging Topic focused on involving diverse

Язык: Английский

---

Enantioselective Alkylation of Primary C(sp³)–H Bonds in N-Methyl Tertiary Amine Enabled by Iridium Complex of Axially Chiral β-Aryl Porphyrins

Journal of the American Chemical Society, Год журнала: 2024, Номер unknown

Опубликована: Ноя. 27, 2024

A fine-tuning of enantioselective carbene insertion into primary C(

Язык: Английский

---

Highly diastereoselective and enantioselective cyclopropanation of alkenes catalyzed by a chiral iridium(III) porphyrin complex

Chem Catalysis, Год журнала: 2025, Номер unknown, С. 101262 - 101262

Опубликована: Фев. 1, 2025

Язык: Английский

---