Browse
Submit Data
Databases
API
Help

Dataset Information

20 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Visible-Light-Driven Intermolecular Reductive Ene-Yne Coupling by Iridium/Cobalt Dual Catalysis for C(sp³ )-C(sp² ) Bond Formation.

ABSTRACT: A new methodology to form C(sp³ )-C(sp² ) bonds by visible-light-driven intermolecular reductive ene-yne coupling has been successfully developed. The process relies on the ability of the Hantzsch ester to contribute in both SET and HAT processes through a unified cobalt and iridium catalytic system. This procedure avoids the use of stoichiometric amounts of reducing metallic reagents, which is translated into high functional-group tolerance and atom economy.

SUBMITTER: Gonzalez MJ

PROVIDER: S-EPMC6916364 | biostudies-literature | 2019 Dec

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Visible-Light-Driven Intermolecular Reductive Ene-Yne Coupling by Iridium/Cobalt Dual Catalysis for C(sp3 )-C(sp2 ) Bond Formation.

González María J MJ Breit Bernhard B

Chemistry (Weinheim an der Bergstrasse, Germany) 20191108 69

A new methodology to form C(sp3 )-C(sp2 ) bonds by visible-light-driven intermolecular reductive ene-yne coupling has been successfully developed. The process relies on the ability of the Hantzsch ester to contribute in both SET and HAT processes through a unified cobalt and iridium catalytic system. This procedure avoids the use of stoichiometric amounts of reducing metallic reagents, which is translated into high functional-group tolerance and atom economy. ...[more]

PMID: 31549749

Similar Datasets

Intermolecular Photocatalytic Chemo-, Stereo- and Regioselective Thiol-Yne-Ene Coupling Reaction.

Project description:The first example of an intermolecular thiol-yne-ene coupling reaction is reported for the one-pot construction of C-S and C-C bonds. Thiol-yne-ene coupling opens a new dimension in building molecular complexity to access densely functionalized products. The employment of Eosin Y/DBU/MeOH photocatalytic system suppresses hydrogen atom transfer (HAT) and associative reductant upconversion (via C-S three-electron σ-bond formation). Investigation of the reaction mechanism by combining online ESI-UHRMS, EPR spectroscopy, isotope labeling, determination of quantum yield, cyclic voltammetry, Stern-Volmer measurements and computational modeling revealed a unique photoredox cycle with four radical-involving stages. As a result, previously unavailable products of the thiol-yne-ene reaction were obtained in good yields with high selectivity. They can serve as stable precursors for synthesizing synthetically demanding activated 1,3-dienes.

| S-EPMC9313788 | biostudies-literature

Synthesis of oximidine II by a copper-mediated reductive ene-yne macrocyclization.

Project description: Not available

| S-EPMC3505758 | biostudies-literature

Visible-Light-Induced Alkoxyl Radicals Enable α-C(sp3)-H Bond Allylation.

Project description:The alkoxyl radical is an essential reactive intermediate in mechanistic studies and organic synthesis with hydrogen atom transfer (HAT) reactivity. However, compared with intramolecular 1,5-HAT or intermolecular HAT of alkoxyl radicals, the intramolecular 1,2-HAT reactivity has been limited to theoretical studies and rarely synthetically utilized. Here we report the first selective 1,2-HAT of alkoxyl radicals for α-C(sp3)-H bond allylation of α-carbonyl, α-cyano, α-trifluoromethyl, and benzylic N-alkoxylphthalimides. The mechanistic probing experiments, electron paramagnetic resonance (EPR) studies, and density functional theory (DFT) calculations confirmed the 1,2-HAT reactivity of alkoxyl radicals, and the use of protic solvents lowered the activation energy by up to 10.4 kcal/mol to facilitate the α-C(sp3)-H allylation reaction.

| S-EPMC6941871 | biostudies-literature

Visible light-induced halogen-atom transfer by N-heterocyclic carbene-ligated boryl radicals for diastereoselective C(sp3)-C(sp2) bond formation.

Project description:Photoinduced halogen-atom transfer (XAT) has rapidly emerged as a programmable approach to generate carbon-centered radical intermediates, mainly relying on silyl and α-aminoalkyl radicals as halogen abstractors. More recently, ligated boryl radicals have also been proposed as effective halogen abstractors under visible-light irradiation. In this study, we describe the use of this approach to enable C(sp3)-C(sp2) bond formation via radical addition of carbon-centered radicals generated via XAT onto chloroalkynes. Our mechanistic investigation reveals a complex interplay of highly reactive radical intermediates which, under optimized conditions, delivered the targeted vinyl chlorides in excellent yields and Z : E ratios. Finally, we demonstrated the synthetic value of these products in transition metal-based cross-coupling reactions.

| S-EPMC11340342 | biostudies-literature

Cobalt-catalyzed nucleophilic addition of the allylic C(sp3)-H bond of simple alkenes to ketones.

Project description:We herein describe a cobalt/Xantphos-catalyzed regioselective addition of simple alkenes to acetophenone derivatives, affording branched homoallylic alcohols in high yields with perfect branch selectivities. The intermediate of the reaction would be a nucleophilic allylcobalt(I) species generated via cleavage of the low reactive allylic C(sp3)-H bond of simple terminal alkenes.

| S-EPMC6122116 | biostudies-literature

Hydrodealkenylative C(sp3)-C(sp2) bond fragmentation.

Project description:Chemical synthesis typically relies on reactions that generate complexity through elaboration of simple starting materials. Less common are deconstructive strategies toward complexity-particularly those involving carbon-carbon bond scission. Here, we introduce one such transformation: the hydrodealkenylative cleavage of C(sp3)-C(sp2) bonds, conducted below room temperature, using ozone, an iron salt, and a hydrogen atom donor. These reactions are performed in nonanhydrous solvents and open to the air; reach completion within 30 minutes; and deliver their products in high yields, even on decagram scales. We have used this broadly functionality tolerant transformation to produce desirable synthetic intermediates, many of which are optically active, from abundantly available terpenes and terpenoid-derived precursors. We have also applied it in the formal total syntheses of complex molecules.

| S-EPMC6625654 | biostudies-literature

Metal-free, intermolecular carbopyridylation of alkenes via visible-light-induced reductive radical coupling.

Project description:An efficient, metal-free strategy for the intermolecular three-component carbopyridylation of styrenes, enabled by Hantzsch ester and visible light, has been described. This versatile protocol gives access to important β-CF3 pyridines, through the regioselective, sequential formation of two C-C bonds without the use of exogenous catalysts. The value of this benign protocol has been demonstrated through functionalizations of natural-product- and drug-based complex molecules.

| S-EPMC6301205 | biostudies-literature

Cobalt-Catalyzed C(sp2)-C(sp3) Suzuki-Miyaura Cross Coupling.

Project description:A cobalt-catalyzed method for the C(sp2)-C(sp3) Suzuki-Miyaura cross coupling of aryl boronic esters and alkyl bromides is described. Cobalt-ligand combinations were assayed with high-throughput experimentation, and cobalt(II) sources with trans-N,N'-dimethylcyclohexane-1,2-diamine (DMCyDA, L1) produced optimal yield and selectivity. The scope of this transformation encompassed steric and electronic diversity on the aryl boronate nucleophile as well as various levels of branching and synthetically valuable functionality on the electrophile. Radical trap experiments support the formation of electrophile-derived radicals during catalysis.

| S-EPMC7867578 | biostudies-literature

Silacyclization through palladium-catalyzed intermolecular silicon-based C(sp2)-C(sp3) cross-coupling.

Project description:Silicon-based cross-coupling has been recognized as one of the most reliable alternatives for constructing carbon-carbon bonds. However, the employment of such reaction as an efficient ring expansion strategy for silacycle synthesis is comparatively little known. Herein, we develop the first intermolecular silacyclization strategy involving Pd-catalyzed silicon-based C(sp2)-C(sp3) cross-coupling. This method allows the modular assembly of a vast array of structurally novel and interesting sila-benzo[b]oxepines with good functional group tolerance. The key to success for this reaction is that silicon atoms have a stronger affinity for oxygen nucleophiles than carbon nucleophiles, and silacyclobutanes (SCBs) have inherent ring-strain-release Lewis acidity.

| S-EPMC8565370 | biostudies-literature

Iridium-catalyzed enantioselective olefinic C(sp2)-H allylic alkylation.

Project description:The first iridium-catalyzed enantioselective olefinic C(sp2)-H allylic alkylation is developed in cooperation with Lewis base catalysis. This reaction, catalyzed by cinchonidine and an in situ generated cyclometalated Ir(i)/phosphoramidite complex, makes use of the latent enolate character of an α,β-unsaturated carbonyl compound, namely coumalate ester, to introduce an allyl group at its α-position in a branched-selective manner in moderate to good yield with good to excellent enantioselectivities (up to 98 : 2 er).

| S-EPMC8179414 | biostudies-literature