18344-26-8Relevant academic research and scientific papers
Probing the Evolution of Palladium Species in Pd@MOF Catalysts during the Heck Coupling Reaction: An Operando X-ray Absorption Spectroscopy Study
Yuan, Ning,Pascanu, Vlad,Huang, Zhehao,Valiente, Alejandro,Heidenreich, Niclas,Leubner, Sebastian,Inge, A. Ken,Gaar, Jakob,Stock, Norbert,Persson, Ingmar,Martín-Matute, Belén,Zou, Xiaodong
, p. 8206 - 8217 (2018)
The mechanism of the Heck C-C coupling reaction catalyzed by Pd@MOFs has been investigated using operando X-ray absorption spectroscopy (XAS) and powder X-ray diffraction (PXRD) combined with transmission electron microscopy (TEM) analysis and nuclear magnetic resonance (1H NMR) kinetic studies. A custom-made reaction cell was used, allowing operando PXRD and XAS data collection using high-energy synchrotron radiation. By analyzing the XAS data in combination with ex situ studies, the evolution of the palladium species is followed from the as-synthesized to its deactivated form. An adaptive reaction mechanism is proposed. Mononuclear Pd(II) complexes are found to be the dominant active species at the beginning of the reaction, which then gradually transform into Pd nanoclusters with 13-20 Pd atoms on average in later catalytic turnovers. Consumption of available reagent and substrate leads to coordination of Cl- ions to their surfaces, which causes the poisoning of the active sites. By understanding the deactivation process, it was possible to tune the reaction conditions and prolong the lifetime of the catalyst.
Asymmetric Umpolung Hydrogenation and Deuteration of Alkenes Catalyzed by Nickel
Guo, Siyu,Wang, Xiuhua,Zhou, Jianrong Steve
supporting information, p. 1204 - 1207 (2020/02/04)
Nickel-catalyzed asymmetric hydrogenation of several types of alkenes proceeds in high enantioselectivity, using acetic acid or water as the hydrogen source and indium powder as electron donor. The scope of alkenes herein include α,β-unsaturated esters, n
Rhenium-catalyzed α-alkylation of enol acetates with alcohols or ethers
Umeda, Rui,Takahashi, Yuuki,Yamamoto, Takaaki,Iseki, Hideki,Osaka, Issey,Nishiyama, Yutaka
supporting information, p. 92 - 101 (2018/11/01)
When benzylic and allylic alcohols were treated with enol acetate in the presence of a catalytic amount of a rhenium complex, ReBr(CO)5, the carbon-carbon bond formation of the alcohols and enol acetate smoothly proceeded to give the corresponding ketones and aldehyde in moderate to good yields. For the reaction of allylic alcohols, γ,δ-unsaturated carbonyl compounds were obtained in good yields. When ethers were used instead of alcohols as the alkylated agent, two alkyl moieties on the ethers were utilized on the reaction.
Palladium-catalyzed site-selective arylation of aliphatic ketones enabled by a transient ligand
Pan, Lei,Yang, Ke,Li, Guigen,Ge, Haibo
supporting information, p. 2759 - 2762 (2018/03/21)
Transition metal-catalyzed direct C-H bond functionalization enabled by transient ligands has become an attractive topic. Here we report a palladium-catalyzed site-selective arylation of β-C(sp3)-H bonds in aliphatic ketones with β-alanine as the transient ligand.
Rhenium complex-catalyzed coupling reaction of enol acetates with alcohols
Umeda, Rui,Takahashi, Yuuki,Nishiyama, Yutaka
supporting information, p. 6113 - 6116 (2015/01/09)
The reaction of enol acetates with alcohols in the presence of a catalytic amount of a rhenium complex, such as ReBr(CO)5, produced the corresponding ketones and aldehydes in moderate to good yields. It was suggested that the preparation of an ether, an intermolecular dehydrated product, was the first step of the reaction.
Vinyl polymerization versus [1,3] O to C rearrangement in the ruthenium-catalyzed reactions of vinyl ethers with hydrosilanes
Harada, Nari-Aki,Nishikata, Takashi,Nagashima, Hideo
, p. 3243 - 3252 (2012/06/01)
Two reactions, vinyl polymerization and [1,3] O to C rearrangement of vinyl ethers, are investigated in the ruthenium-catalyzed reaction with hydrosilanes. The reaction pathways are dependent on the substituents of the vinyl ether, in particular, those of the alkoxy group. Primary-, secondary-, and tertiary-alkyl vinyl ethers, ROCHCH2, are polymerized with ease to give the corresponding polymer in good yields. When R is electron-donating benzyl groups, the reaction does not give the polyvinyl ether but results in [1,3] O to C rearrangement to give the corresponding aldehyde, RCH2CHO in moderate to good yields. The rearrangement selectively proceeds when vinyl ethers having α-substituents are used as the starting materials to give the corresponding ketones in high yields. With catalytic amounts of hydrosilanes, the rearrangement gives ketones or aldehydes selectively. In sharp contrast, use of excess amounts of hydrosilanes leads to the rearrangement followed by reduction of the formed carbonyl group to give the corresponding silyl ethers in good yields. Nature of catalytically active species is discussed. Crown Copyright
InCl3/Me3SiBr-catalyzed direct coupling between silyl ethers and enol acetates
Onishi, Yoshiharu,Nishimoto, Yoshihiro,Yasuda, Makoto,Baba, Akio
supporting information; experimental part, p. 2762 - 2765 (2011/08/02)
A combined Lewis acid catalyst of InCl3 and Me3SiBr promoted the direct use of enol acetates in the coupling with low-reactive silyl ethers, in which functional groups including ketones and aldehydes survived. Sterically hindered silyl ethers such as ROSiEt3, ROSiPh3, ROSit-BuMe2, and ROSii-Pr3 were also applicable.
Synthesis of β-aryl ketones by tetraphosphine/palladium catalysed Heck reactions of 2- or 3-substituted allylic alcohols with aryl bromides
Berthiol, Florian,Doucet, Henri,Santelli, Maurice
, p. 4372 - 4383 (2007/10/03)
Through the use of [PdCl(C3H5)]2/cis,cis,cis-1,2,3,4-tetrakis(diphenylphosphinomethyl)cyclopentane as a catalyst, a range of aryl bromides undergoes Heck reaction using 2- or 3-subtituted allylic alcohols. With these sterically congested alkenes, the selective formation of β-aryl ketones was observed when appropriate reaction conditions were used. The influence of the functional group on the aryl bromide and of the base on the selectivity is remarkable. With several substrates, much higher selectivities were obtained using NaHCO3 instead of K2CO3 as base. Furthermore, this catalyst can be used at low loading with several substrates.
Osmium-Promoted Electrophilic Substitution of Anisoles: A Versatile New Method for the Incorporation of Carbon Substituents
Kolis, Stanley P.,Kopach, Michael E.,Liu, Ronggang,Harman, W. Dean
, p. 130 - 136 (2007/10/03)
A structurally and electronically diverse set of anisoles are dihapto-coordinated to the π-base pentaammineosmium(II) and treated with a variety of carbon electrophiles (e.g. Michael acceptors, acetals) After deprotonation of a 4H-anisolium intermediate with a tertiary amine base, C(4)-substituted anisole complexes are isolated. The functionalized arenes are removed from the metal center either by mild heating or treatment with an oxidant (e.g. AgOTf, DDQ, CAN). The resulting substituted anisoles are isolated with yields ranging from 55-95%.
Palladium(II)-Catalyzed Conjugate Addition of Aromatics to α,β-Unsaturated Ketones and Aldehydes with Arylantimony Compounds
Cho, Chan Sik,Motofusa, Shin-Ichi,Ohe, Kouichi,Uemura, Sakae
, p. 2341 - 2348 (2007/10/03)
Triarylstibines react with α,β-unsaturated ketones and aldehydes in acetic acid at room temperature in the presence of AgOAc and a catalytic amount of Pd(OAc)2 to afford the conjugate addition products (the formal hydroarylated compounds to an olefinic part) in good yields. In contrast, diarylantimony chlorides, arylantimony dichlorides, and diphenylantimony acetate react with the enones and enals even in the absence of AgOAc to afford the same products in higher yields compared with those from triarylstibines. These are new C-C bond-forming reactions using arylantimony(III) compounds in which the formation of a palladium enolate or a trivalent antimony enolate is proposed as an intermediate.
