Mesoionic Carbene‐Catalyzed Formyl Alkylation of Aldehydes

Angewandte Chemie International Edition, Journal Year: 2023, Volume and Issue: 62(24)

Published: April 18, 2023

Ketones are among the most useful functional groups in organic synthesis, and they commonly encountered a broad range of compounds with various applications. Herein, we describe mesoionic carbene-catalyzed coupling reaction aldehydes non-activated secondary even primary alkyl halides. This metal-free method utilizes deprotonated Breslow intermediates derived from carbenes (MICs), which act as super electron donors induce single-electron reduction mild has substrate scope tolerates many groups, allows to prepare diversity simple ketones well bio-active molecules by late-stage functionalization.

Language: Английский

---

Organocatalytic C−H Functionalization of Simple Alkanes

Angewandte Chemie International Edition, Journal Year: 2023, Volume and Issue: 62(45)

Published: Sept. 21, 2023

The direct functionalization of inert C(sp3 )-H bonds to form carbon-carbon and carbon-heteroatom offers vast potential for chemical synthesis therefore receives increasing attention. At present, most successes come from strategies using metal catalysts/reagents or photo/electrochemical processes. use organocatalysis this purpose remains scarce, especially when dealing with challenging C-H such as those simple alkanes. Here we disclose the first organocatalytic functionalization/acylation completely unfunctionalized Our approach involves N-heterocyclic carbene catalyst-mediated carbonyl radical intermediate generation coupling alkanes (through corresponding alkyl intermediates generated via a hydrogen atom transfer process). Unreactive are widely present in fossil fuel feedstocks, commercially important organic polymers, complex molecules natural products. study shall inspire new avenue quick these under light- metal-free catalytic conditions.

Language: Английский

---

1H-1,2,3-Triazol-5-ylidenes as Catalytic Organic Single-Electron Reductants

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(5), P. 2933 - 2938

Published: Jan. 22, 2024

Most of the known single-electron reductants are either metal based reagents, used in a stoichiometric amount, or combination an organic species and photocatalyst. Here we report that 1

Language: Английский

---

Skeletal Transformation of Unactivated Arenes Enabled by a Low-Temperature Dearomative (3 + 2) Cycloaddition

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(22), P. 12214 - 12223

Published: May 24, 2023

Simple aromatic compounds like benzene are abundant feedstocks, for which the preparation of derivatives chiefly begins with electrophilic substitution reactions or, less frequently, reductions. Their high stability makes them particularly reluctant to participate in cycloadditions under ordinary reaction conditions. Here, we demonstrate exceptional ability 1,3-diaza-2-azoniaallene cations undergo formal (3 + 2) unactivated below room temperature, providing thermally stable dearomatized adducts on a multi-gram scale. The cycloaddition, tolerates polar functional groups, activates ring toward further elaboration. On treatment dienophiles, cycloadducts (4 cycloaddition–cycloreversion cascade yield substituted or fused arenes, including naphthalene derivatives. overall sequence results transmutation arenes through an exchange carbons: two-carbon fragment from original is replaced another incoming dienophile, introducing unconventional disconnection synthesis ubiquitous building blocks. Applications this two-step acenes, isotopically labeled molecules, and medicinally relevant demonstrated.

Language: Английский

---

Homologation of Ketones: Direct Transformation of Alkyl Ketones to Aryl Ketones via Photoredox Catalyzed Deacylation-Aroylation Sequence

Organic Letters, Journal Year: 2024, Volume and Issue: 26(32), P. 6915 - 6920

Published: Aug. 8, 2024

Ketones, as essential functional group skeletons, have garnered significant interest due to their diverse transformations. Herein, we describe a versatile photoredox catalyzed deacylation-aroylation strategy that enables the direct transformation of alkyl ketones aryl ketones. This process involves deacylation dihydroquinazolinones derived from generate radicals, followed by subsequent NHC-catalyzed or NHC-mediated radical aroylation.

Language: Английский

---

Switching Mesoionic Carbene-Organocatalysis from Radical to Ionic Pathway through Base-Controlled Formation of Breslow Intermediates versus Breslow Enolates

Chemical Science, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 1, 2025

N-heterocyclic carbene (NHC) organocatalysis has experienced significant advancements. Two distinct reaction pathways have been developed, ionic and radical, through Breslow intermediates (BIs) enolates (BI-s), respectively. The ability to selectively generate these is crucial for optimizing outcomes. In this paper we show that with mesoionic carbenes (MICs) it possible control the formation of BIs versus BI-s, use weak bases strong bases, Of particular interest coupling aldehydes alkyl halides yield ketones via an pathway.

Language: Английский

---

Redox-Paired Reductive Heck Reaction and Oxidative Esterification Catalyzed by Mesoionic Carbenes

Organic Letters, Journal Year: 2024, Volume and Issue: 26(35), P. 7419 - 7424

Published: Aug. 22, 2024

Paring a reductive reaction and an oxidative in one could be immensely important achieving atom economic environmental advantages. Herein, we report simple protocol that combines two such Heck reactions esterification by using mesoionic carbenes as catalysts to synthesize multiple valuable products under mild conditions.

Language: Английский

---

N‐Heterocyclic Carbenes (NHCs)‐Catalyzed Coupling Reactions of Aldehydes and Organic Halides

ChemCatChem, Journal Year: 2023, Volume and Issue: 16(3)

Published: Nov. 23, 2023

Abstract This concept aims to summarize the direct coupling of aldehydes and organic halides (including activated unactivated halides) catalyzed by N ‐heterocyclic carbenes (NHCs). The key factor this transformation is formation Breslow intermediates, which are either nucleophilic or reductive. Additionally, activation inert C−H bond also was reviewed in performance via processes single electron transfer (SET) subsequent intramolecular 1, n ‐ hydrogen atom (HAT) intermolecular HAT. Finally, differences reactivity various generated from different NHCs, have been discussed give a deeper understanding ongoing popularity NHC‐organocatalysis.

Language: Английский

---

Enones from aldehydes and alkenes by carbene-catalyzed dehydrogenative couplings

Chinese Chemical Letters, Journal Year: 2024, Volume and Issue: 35(9), P. 109495 - 109495

Published: Jan. 12, 2024

Language: Английский

---

Ambiphilic Alcohol Dehydrogenation by BICAAC Mimicking Metal–Ligand Cooperativity

ACS Catalysis, Journal Year: 2024, Volume and Issue: 14(10), P. 8087 - 8095

Published: May 8, 2024

In this report, an unusual bond activation strategy has been demonstrated by BICAAC, which essentially emulates the behavior of a transition metal. The ambiphilic nature specific carbene facilitated simultaneous proton and hydride capture from alcohol molecule to carry out smooth dehydrogenation under mild conditions. route closely follows traditional metal–ligand bifunctional substrate. hydrogen extracted substrate becomes stored in carbon, unambiguously ascertained isolation intermediate its X-ray crystallographic characterization. Such event further interrogated detail deuterium-labeling experiment DFT computations substantiate critical role carbene's ambiphilicity. Additionally, delivered situ-generated olefinic completely mimic borrowing reaction organocatalytic fashion. Both rehydrogenation reactions have conducted single pot using BICAAC as catalyst that alkylates fluorene at 9-position series alcohols alkyl source. A thorough mechanistic sketch describes involvement radical for latter part reaction, overall bringing different outlook carbene-promoted small-molecule reactions.

Language: Английский

---