Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Amide directed iridium C(sp³)-H borylation catalysis with high N-methyl selectivity.

ABSTRACT: A bidentate monoanionic ligand system was developed to enable iridium catalyzed C(sp³)-H activation borylation of N-methyl amides. Borylated amides were obtained in moderate to good isolated yields, and exclusive mono-borylation allowed the amide to be the limiting reagent. Selectivity for C(sp³)-H activation was demonstrated in the presence of sterically available C(sp³)-H bonds. Competitive kinetic isotope studies revealed a large primary isotope effect, implicating C-H activation as the rate limiting step.

SUBMITTER: Dannatt JE

PROVIDER: S-EPMC9854009 | biostudies-literature | 2022 Mar

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Amide directed iridium C(sp3)-H borylation catalysis with high N-methyl selectivity.

Dannatt Jonathan E JE Yadav Anshu A Smith Milton R MR Maleczka Robert E RE

Tetrahedron 20211126

A bidentate monoanionic ligand system was developed to enable iridium catalyzed C(sp3)-H activation borylation of N-methyl amides. Borylated amides were obtained in moderate to good isolated yields, and exclusive mono-borylation allowed the amide to be the limiting reagent. Selectivity for C(sp3)-H activation was demonstrated in the presence of sterically available C(sp3)-H bonds. Competitive kinetic isotope studies revealed a large primary isotope effect, ...[more]

PMID: 36684041

Similar Datasets

Iridium-Catalyzed, Hydrosilyl-Directed Borylation of Unactivated Alkyl C-H Bonds.

Project description:We report the iridium-catalyzed borylation of primary and secondary alkyl C-H bonds directed by a Si-H group to form alkylboronate esters site selectively. The reactions occur with high selectivity at primary C-H bonds γ to the hydrosilyl group to form primary alkyl bisboronate esters. In the absence of such primary C-H bonds, the borylation occurs selectively at a secondary C-H bond γ to the hydrosilyl group, and these reactions of secondary C-H bonds occur with high diastereoselectivity. The hydrosilyl-containing alkyl boronate esters formed by this method undergo transformations selectively at the carbon-boron or carbon-silicon bonds of these products under distinct conditions to give the products of amination, oxidation, and arylation.

| S-EPMC4809204 | biostudies-literature

Cobalt-Catalyzed, Aminoquinoline-Directed Functionalization of Phosphinic Amide sp2 C-H Bonds.

Project description:In this paper, we introduce arylphosphinic acid aminoquinoline amides as competent substrates for cobalt-catalyzed sp2 C-H bond functionalization. Specifically, the feasibility of their coupling with alkynes, alkenes, and allyl pivalate has been demonstrated. Reactions are catalyzed by simple Co(NO3)2 hydrate in ethanol or mixed dioxane/tBuOH solvent in the presence of Mn(OAc)3·2H2O additive, sodium pivalate, or acetate base and use oxygen from the air as an oxidant. Directing group removal affords ortho-functionalized P,P-diarylphosphinic acids.

| S-EPMC4980089 | biostudies-literature

A practical preparation of bicyclic boronates via metal-free heteroatom-directed alkenyl sp2-C‒H borylation.

Project description:Bicyclic boronates play critical roles in the discovery of functional materials and antibacterial agents, especially against deadly bacterial pathogens. Their practical and convenient preparation is in high demand but with great challenge. Herein, we report an efficient strategy for the preparation of bicyclic boronates through metal-free heteroatom-directed alkenyl sp2-C‒H borylation. This synthetic approach exhibits good functional group compatibility, and the corresponding boronates bearing halides, aryls, acyclic and cyclic frameworks are obtained with high yields (43 examples, up to 95% yield). Furthermore, a gram-scale experiment is conducted, and downstream transformations of the bicyclic boronates are pursued to afford natural products, drug scaffolds, and chiral hemiboronic acid catalysts.

| S-EPMC10447525 | biostudies-literature

Effect of Pincer Methylation on the Selectivity and Activity in (PNP)Cobalt-Catalyzed C(sp2)-H Borylation.

Project description:Cobalt complexes supported by a tetramethylated PNP pincer ligand (Me4 iPrPNP = 2,6-(iPr2PCMe2)2(C5H3N)) have been synthesized and structurally characterized. Examples include cobalt(I)-choride, -methyl, -aryl and -benzofuranyl derivatives. The performance of these compounds was evaluated in the catalytic borylation of fluorinated arenes using B2Pin2 as the boron source. While P-C bond cleavage, a known deactivation pathway in [(PNP)Co]-catalyzed borylation was suppressed, the overall activity and selectivity of the borylation of fluoroarenes was reduced as compared to the previously reported [(PNP)Co] catalyst lacking isopropylene spacers. Stoichiometric reactions support an increased barrier for oxidative addition to cobalt(I), a result of the increased steric profile and decreased conformational flexibility of the pincer resulting from methylation distal to the active site. With a more activated substrate such as benzofuran, catalytic borylation with cobalt(I) precatalysts and HBPin was observed. Monitoring the progress of the reaction by NMR spectroscopy revealed the presence of cobalt(III) intermediates during the course of the borylation, supporting a cobalt(I)-(III) redox cycle.

| S-EPMC8656436 | biostudies-literature

Mechanism, reactivity, and selectivity of the iridium-catalyzed C(sp3)-H borylation of chlorosilanes.

Project description:The iridium-catalyzed C(sp3)-H borylation of methylchlorosilanes is investigated by means of density functional theory, using the B3LYP and M06 functionals. The calculations establish that the resting state of the catalyst is a seven-coordinate Ir(v) species that has to be converted into an Ir(iii)tris(boryl) complex in order to effect the oxidative addition of the C-H bond. This is then followed by a C-B reductive elimination to yield the borylated product, and the catalytic cycle is finally completed by the regeneration of the active catalyst over two facile steps. The two employed functionals give somewhat different conclusions concerning the nature of the rate-determining step, and whether reductive elimination occurs directly or after a prior isomerization of the Ir(v) hydride intermediate complex. The calculations reproduce quite well the experimentally-observed trends in the reactivities of substrates with different substituents. It is demonstrated that the reactivity can be correlated to the Ir-C bond dissociation energies of the corresponding Ir(v) hydride intermediates. The effect of the chlorosilyl group is identified to originate from the α-carbanion-stabilizing effect of the silicon, which is further reinforced by the presence of an electron-withdrawing chlorine substituent. Furthermore, the source of selectivity for the borylation of primary over secondary C(sp3)-H can be explained on a steric basis, by repulsion between the alkyl group and the Ir/ligand moiety. Finally, the difference in the reactivity between C(sp3)-H and C(sp2)-H borylation is investigated and rationalized in terms of distortion/interaction analysis.

| S-EPMC5644124 | biostudies-literature

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

Project description: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.

| S-EPMC6916364 | biostudies-literature

Amide-directed photoredox-catalysed C-C bond formation at unactivated sp3 C-H bonds.

Project description:Carbon-carbon (C-C) bond formation is paramount in the synthesis of biologically relevant molecules, modern synthetic materials and commodity chemicals such as fuels and lubricants. Traditionally, the presence of a functional group is required at the site of C-C bond formation. Strategies that allow C-C bond formation at inert carbon-hydrogen (C-H) bonds enable access to molecules that would otherwise be inaccessible and the development of more efficient syntheses of complex molecules. Here we report a method for the formation of C-C bonds by directed cleavage of traditionally non-reactive C-H bonds and their subsequent coupling with readily available alkenes. Our methodology allows for amide-directed selective C-C bond formation at unactivated sp3 C-H bonds in molecules that contain many such bonds that are seemingly indistinguishable. Selectivity arises through a relayed photoredox-catalysed oxidation of a nitrogen-hydrogen bond. We anticipate that our findings will serve as a starting point for functionalization at inert C-H bonds through a strategy involving hydrogen-atom transfer.

| S-EPMC5574171 | biostudies-literature

Palladium-catalyzed, aminoquinoline-directed arylation of phosphonamidate and phosphinic amide sp3 C-H bonds.

Project description:Aminoquinoline-directed, palladium-catalyzed sp3 C-H bond arylation in phosphonamidates and phosphinic amides is reported. The reaction employs Pd(OAc)2 as a catalyst at 10 mol% loading and cesium phosphate or potassium carbonate as a base in 1,2-dichlorobenzene as a solvent. The directing group can be removed under basic conditions to afford phosphonic acid esters. The chemistry described here is the first example of unactivated sp3 C-H bond arylation by using a phosphorus-containing directing group.

| S-EPMC5479433 | biostudies-literature

Metal-free, photoinduced remote C(sp3)-H borylation.

Project description:Here, we describe a protocol for the metal-free, photo-induced borylation of unactivated C(sp3)-H bonds distal to an O-oxalate hydroxamic ester functionality. The methodology requires only substrate and bis(catecholato)diboron under light irradiation to effect the desired transformation. A range of linear and cyclic tertiary and secondary borylation products are obtained in good yields and high site-selectivity enabling the late-stage C(sp3)-H borylation of natural product derivatives and drug-like compounds.

| S-EPMC10498503 | biostudies-literature

Hydroxy-directed iridium-catalyzed enantioselective formal β-C(sp2)-H allylic alkylation of α,β-unsaturated carbonyls.

Project description:Hydroxy-directed iridium-catalyzed enantioselective formal β-C(sp2)-H allylic alkylation of kojic acid and structurally related α,β-unsaturated carbonyl compounds is developed. This reaction, catalyzed by an Ir(i)/(P,olefin) complex, utilizes the nucleophilic character of α-hydroxy α,β-unsaturated carbonyls, to introduce an allyl group at its β-position in a branched-selective manner in good to excellent yield with uniformly high enantioselectivity (up to >99.9 : 0.1 er). To the best of our knowledge, this report represents the first example of the use of kojic acid in a transition metal catalyzed highly enantioselective transformation.

| S-EPMC9629034 | biostudies-literature