Nitrene-mediated intermolecular N–N coupling for efficient synthesis of hydrazides

Nature Chemistry, Год журнала: 2021, Номер 13(4), С. 378 - 385

Опубликована: Март 22, 2021

Язык: Английский

---

Mechanistic snapshots of rhodium-catalyzed acylnitrene transfer reactions

Science, Год журнала: 2023, Номер 381(6657), С. 525 - 532

Опубликована: Июль 20, 2023

Rhodium (Rh) acylnitrene complexes are widely implicated in catalytic C-H amidation reactions but have eluded isolation and structural characterization. To overcome this challenge, we designed a chromophoric octahedral Rh complex with bidentate dioxazolone ligand, which photoinduced metal-to-ligand charge transfer initiates amidation. X-ray photocrystallographic analysis of the Rh-dioxazolone allowed elucidation targeted Rh-acylnitrenoid provided firm evidence that singlet nitrenoid species is primarily responsible for acylamino reactions. We also monitored crystallo reaction nucleophile situ-generated Rh-acylnitrenoid, crystallographically traceable system to capture mechanistic snapshots transfer.

Язык: Английский

---

Plausible Rh(V) Intermediates in Catalytic C–H Activation Reactions

ACS Catalysis, Год журнала: 2017, Номер 8(1), С. 242 - 257

Опубликована: Ноя. 20, 2017

Catalysis by defined transition-metal complexes has captivated the attention of scientific community over last decades. The well-documented utility Rh(III) in C–H activation reactions have enabled development a plethora new catalytic methods. High-valent species were first predicted palladium-based transformations. From those early studies, it was apparent that differences reactivity and selectivity could be expected. By analogy, higher valent Rh(V) represent approach offer different opportunities to improve broaden current state-of-the-art field.

Язык: Английский

---

C−H Bond Functionalization by Mechanochemistry

Chemistry - A European Journal, Год журнала: 2017, Номер 23(68), С. 17157 - 17165

Опубликована: Авг. 24, 2017

The advances made in the mechanosynthesis of inorganic and organometallic complexes excellent past developments with metal-catalyzed cross-coupling reactions by high-speed ball milling have sufficienly laid ground work for merging C-H functionalization mechanochemical techniques. In recent years, fast development activation given us examples olefinations, amidations, halogenations, oxidative couplings, among others. This concept article will describe some events that led to activation, current state-of-the-art, present challenges this merge, unique scenarios which mechanochemistry could complement traditional solution-based approaches.

Язык: Английский

---

Mechanochemical Rhodium(III)-Catalyzed C–H Bond Amidation of Arenes with Dioxazolones under Solventless Conditions in a Ball Mill

ACS Catalysis, Год журнала: 2017, Номер 7(7), С. 4592 - 4596

Опубликована: Июнь 5, 2017

A procedure for the direct mechanochemical rhodium(III)-catalyzed C–H bond amidation of arenes with 1,4,2-dioxazol-5-ones as nitrogen source has been developed. The transformation proceeds under solventless conditions and does not require additional heating. corresponding ortho amidated products are formed in high yields shorter reaction times than solution.

Язык: Английский

---

Intermolecular, Branch‐Selective, and Redox‐Neutral Cp*Ir^III‐Catalyzed Allylic C−H Amidation

Angewandte Chemie International Edition, Год журнала: 2019, Номер 58(21), С. 7117 - 7121

Опубликована: Март 20, 2019

Abstract Herein, we report the redox‐neutral, intermolecular, and highly branch‐selective amidation of allylic C−H bonds enabled by Cp*Ir III catalysis. A variety readily available carboxylic acids were converted into corresponding dioxazolones efficiently coupled with terminal internal olefins in high yields selectivities. Mechanistic investigations support formation a nucleophilic Ir –allyl intermediate rather than direct insertion an Ir–nitrenoid species bond.

Язык: Английский

---

Non-C₂-Symmetric Chiral-at-Ruthenium Catalyst for Highly Efficient Enantioselective Intramolecular C(sp³)–H Amidation

Journal of the American Chemical Society, Год журнала: 2019, Номер 141(48), С. 19048 - 19057

Опубликована: Ноя. 21, 2019

A new class of chiral ruthenium catalysts is introduced in which cyclometalated by two 7-methyl-1,7-phenanthrolinium heterocycles, resulting chelating pyridylidene remote N-heterocyclic carbene ligands (rNHCs). The overall chirality results from a stereogenic metal center featuring either Λ or Δ absolute configuration. This work features the importance relative metal-centered stereochemistry. Only non-C2-symmetric chiral-at-ruthenium complexes display unprecedented catalytic activity for intramolecular C(sp3)–H amidation 1,4,2-dioxazol-5-ones to provide γ-lactams with up 99:1 er and catalyst loadings down 0.005 mol % (up 11 200 TON), while C2-symmetric diastereomer favors an undesired Curtius-type rearrangement. DFT calculations elucidate origins superior C–H reactivity displayed compared related counterparts.

Язык: Английский

---

Nitrene Transfer Reactions for Asymmetric C–H Amination: Recent Development

European Journal of Organic Chemistry, Год журнала: 2019, Номер 2020(8), С. 909 - 916

Опубликована: Дек. 18, 2019

C–H bonds are ubiquitous and abundant in organic molecules. If could be directly converted to desired functional groups a chemo‐, site‐, stereoselective manner, functionalization would strong useful tool for synthesis. Recent developments catalytic enzymatic chemistry have achieved highly sustainable selective nitrene insertion. Initially, amination was inspired by model studies on oxidation used iminoiodinanes, nitrogen analogs of iodosobenzene, as precursors. Transition‐metal/iminoiodinane systems well studied established. These can introduce sulfonamide with excellent stereoselectivity, albeit co‐production iodobenzene waste material. Fortunately, the atom economics this methodology were improved introducing sources such azide compounds 1,2,4‐dioxazol‐5‐one derivatives. In review, we present details these respect their catalysts sources.

Язык: Английский

---

Cobalt(III)- and Rhodium(III)-Catalyzed C–H Amidation and Synthesis of 4-Quinolones: C–H Activation Assisted by Weakly Coordinating and Functionalizable Enaminone

Organic Letters, Год журнала: 2017, Номер 19(7), С. 1812 - 1815

Опубликована: Март 30, 2017

Cobalt(III) and rhodium(III) catalysts exhibited complementary scope in C–H amidation of aryl enaminones. The reactions proceeded with broad under the assistance a weakly coordinating bifunctional enaminone directing group. electrophilicity group can be further utilized subsequent hydrolysis–cyclization to afford NH 4-quinolones telescoping reactions.

Язык: Английский

---

Cp*Rh(III)/Bicyclic Olefin Cocatalyzed C–H Bond Amidation by Intramolecular Amide Transfer

Journal of the American Chemical Society, Год журнала: 2017, Номер 139(18), С. 6506 - 6512

Опубликована: Апрель 18, 2017

A bicyclic olefin was discovered as a cocatalyst in Cp*Rh(III)-catalyzed C–H bond amidation proceeding by an intramolecular amide transfer N-phenoxyacetamide derivatives. Combining experimental and theoretical studies, we propose that the promotes Rh(III) intermediate to undergo oxidative addition into O–N form Rh(V) nitrenoid species subsequently direct add ortho position. The directing group plays dual role cleavable coordinating moiety well essential coupling partner for amidation. This methodology successfully applied late-stage diversification of natural products marketed drug under mild conditions.

Язык: Английский

---