Browse
Submit Data
Databases
API
Help

Dataset Information

10 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Nickel-catalyzed insertions of vinylidenes into Si-H bonds.

ABSTRACT: A nickel-catalyzed reductive cyclization of 1,1-dichloroalkenyl silanes is reported. The products of this reaction are unsaturated five- or six-membered silacycles. Intermolecular variants are also described, providing access to trisubstituted vinyl silanes that are not accessible by alkyne hydrosilylation or sila-Heck-type processes. A variety of silanes can be utilized, including those that serve as nucleophilic partners in Hiyama cross-coupling reactions. Mechanistic studies using deuterium-labelled silanes are described.

SUBMITTER: Biswas S

PROVIDER: S-EPMC7679053 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Similar Datasets

Nickel Catalyzed Vinylidene Insertions into O-H Bonds.

Project description:A (pybox)Ni catalyst (pybox = pyridine-bis(oxazoline)) promotes the reductive cyclization of β-hydroxy 1,1-dichloroalkenes to form 2,3-dihydrofurans. The substrates for this reaction are conveniently prepared by an aldol addition followed by one-carbon homologation. Chiral substrates are accessible in highly enantioenriched form, allowing for the synthesis of stereochemically complex 2,3,4-trisubstituted products. Mechanistic studies support a vinylidene O-H insertion pathway rather than C-O cross-coupling followed by reductive dechlorination.

| S-EPMC8115312 | biostudies-literature

Activation of Si-Si Bonds for Copper(I)-Catalyzed Conjugate Silylation.

Project description:Several alkyl- and vinylsilanes were prepared through the copper(I)-catalyzed conjugate silylation of ?,?-unsaturated compounds. Optimal reaction conditions were first investigated to realize the conjugate addition of a nucleophilic silicon species to poorly electrophilic acceptors such as phenylvinyl sulfone by cleavage of the Si-Si bond of a disilane reagent. The scope of this reaction was extended to various electrophiles bearing different electron-withdrawing groups and afforded the desired substituted alkyl- and vinylsilanes. Among the wide range of commercially available disilanes, the reactivities of alkyl-, aryl-, and ethoxydisilane were also examined.

| S-EPMC3510700 | biostudies-literature

Nickel-catalyzed trifluoromethylthiolation of Csp<sup>2</sup>-O bonds.

Project description:While nickel catalysts have previously been shown to activate even the least reactive Csp2-O bonds, i.e. aryl ethers, in the context of C-C bond formation, little is known about the reactivity limits and molecular requirements for the introduction of valuable functional groups under homogeneous nickel catalysis. We identified that due to the high reactivity of Ni-catalysts, they are also prone to react with existing or installed functional groups, which ultimately causes catalyst deactivation. The scope of the Ni-catalyzed coupling protocol will therefore be dictated by the reactivity of the functional groups towards the catalyst. Herein, we showed that the application of computational tools allowed the identification of matching functional groups in terms of suitable leaving groups and tolerated functional groups. This allowed for the development of the first efficient protocol to trifluoromethylthiolate Csp2-O bonds, giving the mild and operationally simple C-SCF3 coupling of a range of aryl, vinyl triflates and nonaflates. The novel methodology was also applied to biologically active and pharmaceutical relevant targets, showcasing its robustness and wide applicability.

| S-EPMC5635847 | biostudies-literature

Nickel-Catalyzed Activation of Acyl C-O Bonds of Methyl Esters.

Project description:We report the first catalytic method for activating the acyl C-O bonds of methyl esters through an oxidative-addition process. The oxidative-addition adducts, formed using nickel catalysis, undergo in?situ trapping to provide anilide products. DFT calculations are used to support the proposed reaction mechanism, to understand why decarbonylation does not occur competitively, and to elucidate the beneficial role of the substrate structure and the Al(OtBu)3 additive on the kinetics and thermodynamics of the reaction.

| S-EPMC4821830 | biostudies-literature

Allene formation by gold catalyzed cross-coupling of masked carbenes and vinylidenes.

Project description:Addition of a sterically demanding cyclic (alkyl)(amino)carbene (CAAC) to AuCl(SMe(2)) followed by treatment with [Et(3)Si(Tol)](+)[B(C(6)F(5))(4)](-) in toluene affords the isolable [(CAAC)Au(eta(2)-toluene)](+)[B(C(6)F(5))(4)](-) complex. This cationic Au(I) complex efficiently mediates the catalytic coupling of enamines and terminal alkynes to yield allenes and not propargyl amines as observed with other catalysts. Mono-, di-, and tri-substituted enamines can be used, as well as aryl-, alkyl-, and trimethylsilyl-substituted terminal alkynes. The reaction tolerates sterically hindered substrates and is diastereoselective. This general catalytic protocol directly couples two unsaturated carbon centers to form the three-carbon allenic core. The reaction most probably proceeds through an unprecedented "carbene/vinylidene cross-coupling."

| S-EPMC1959421 | biostudies-literature

Nickel-catalyzed coupling reactions of alkyl electrophiles, including unactivated tertiary halides, to generate carbon-boron bonds.

Project description:Through the use of a catalyst formed in situ from NiBr(2)·diglyme and a pybox ligand (both of which are commercially available), we have achieved our first examples of coupling reactions of unactivated tertiary alkyl electrophiles, as well as our first success with nickel-catalyzed couplings that generate bonds other than C-C bonds. Specifically, we have determined that this catalyst accomplishes Miyaura-type borylations of unactivated tertiary, secondary, and primary alkyl halides with diboron reagents to furnish alkylboronates, a family of compounds with substantial (and expanding) utility, under mild conditions; indeed, the umpolung borylation of a tertiary alkyl bromide can be achieved at a temperature as low as -10 °C. The method exhibits good functional-group compatibility and is regiospecific, both of which can be issues with traditional approaches to the synthesis of alkylboronates. In contrast to seemingly related nickel-catalyzed C-C bond-forming processes, tertiary halides are more reactive than secondary or primary halides in this nickel-catalyzed C-B bond-forming reaction; this divergence is particularly noteworthy in view of the likelihood that both transformations follow an inner-sphere electron-transfer pathway for oxidative addition.

| S-EPMC3384763 | biostudies-literature

Hydrosilane σ-Adduct Intermediates in an Adaptive Zinc-Catalyzed Cross-dehydrocoupling of Si-H and O-H Bonds.

Project description:Three-coordinate Ph BOX Me2 ZnR (Ph BOX Me2 =phenyl-(4,4-dimethyl-oxazolinato; R=Me: 2 a, Et: 2 b) catalyzes the dehydrocoupling of primary or secondary silanes and alcohols to give silyl ethers and hydrogen, with high turnover numbers (TON; up to 107 ) under solvent-free conditions. Primary and secondary silanes react with small, medium, and large alcohols to give various degrees of substitution, from mono- to tri-alkoxylation, whereas tri-substituted silanes do not react with MeOH under these conditions. The effect of coordinative unsaturation on the behavior of the Zn catalyst is revealed through a dramatic variation of both rate law and experimental rate constants, which depend on the concentrations of both the alcohol and hydrosilane reactants. That is, the catalyst adapts its mechanism to access the most facile and efficient conversion. In particular, either alcohol or hydrosilane binds to the open coordination site on the Ph BOX Me2 ZnOR catalyst to form a Ph BOX Me2 ZnOR(HOR) complex under one set of conditions or an unprecedented σ-adduct Ph BOX Me2 ZnOR(H-SiR'3 ) under other conditions. Saturation kinetics provide evidence for the latter species, in support of the hypothesis that σ-bond metathesis reactions involving four-centered electrocyclic 2σ-2σ transition states are preceded by σ-adducts.

| S-EPMC8362191 | biostudies-literature

Mechanistic Investigation of Biocatalytic Heme Carbenoid Si-H Insertions.

Project description:Recent studies reported the development of biocatalytic heme carbenoid Si-H insertions for the selective formation of carbon-silicon bonds, but many mechanistic questions remain unaddressed. To this end, a DFT mechanistic investigation was performed which reveals an FeII-based concerted hydride transfer mechanism with early transition state feature. The results from these computational analyses are consistent with experimental data of radical trapping, kinetic isotope effects, and structure-reactivity data using engineered variants of hemoproteins. Detailed geometric and electronic profiles along the heme catalyzed Si-H insertion pathways were provided to help understand the origin of experimental reactivity trends. Quantitative relationships between reaction barriers and some properties such as charge transfer from substrate to heme carbene and Si-H bond length change from reactant to transition state were found. Results suggest catalyst modifications to facilitate the charge transfer from the silane substrate to the carbene, which was determined to be a major electronic driving force of this reaction, should enable the development of improved biocatalysts for Si-H carbene insertion reactions.

| S-EPMC6699785 | biostudies-literature

Nickel-Catalyzed, Reductive C(sp<sup>3</sup> )-Si Cross-Coupling of α-Cyano Alkyl Electrophiles and Chlorosilanes.

Project description:A nickel/zinc-catalyzed cross-electrophile coupling of alkyl electrophiles activated by an α-cyano group and chlorosilanes is reported. Elemental zinc is the stoichiometric reductant in this reductive coupling process. By this, a C(sp3 )-Si bond can be formed starting from two electrophilic reactants whereas previous methods rely on the combination of carbon nucleophiles and silicon electrophiles or vice versa.

| S-EPMC8456968 | biostudies-literature

Experimental and computational evidence for gold vinylidenes: generation from terminal alkynes via a bifurcation pathway and facile C-H insertions.

Project description:Facile cycloisomerization of (2-ethynylphenyl)alkynes is proposed to be promoted synergistically by two molecules of BrettPhosAuNTf(2), affording tricyclic indenes in mostly good yields. A gold vinylidene is most likely generated as one of the reaction intermediates on the basis of both mechanistic studies and theoretical calculations. Different from the well-known Rh, Ru, and W counterparts, this novel gold species is highly reactive and undergoes facile intramolecular C(sp(3))-H insertions as well as O-H and N-H insertions. The formation step for the gold vinylidene is predicted theoretically to be complex with a bifurcated reaction pathway. A pyridine N-oxide acts as a weak base to facilitate the formation of an alkynylgold intermediate, and the bulky BrettPhos ligand in the gold catalyst likely plays a role in sterically steering the reaction toward formation of the gold vinylidene.

| S-EPMC3257394 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data