74663-75-5Relevant articles and documents
Palladium/Copper-Cocatalyzed Arylsilylation of Internal Alkynes with Acyl Fluorides and Silylboranes: Synthesis of Tetrasubstituted Alkenylsilanes by Three-Component Coupling Reaction
Chen, Qiang,Li, Zhenyao,Nishihara, Yasushi
supporting information, p. 385 - 389 (2022/01/15)
In this Letter, the palladium/copper-cocatalyzed arylsilylation of internal alkynes with acyl fluorides and silylboranes is described. This is the first example in which acyl fluorides have been utilized for the three-component coupling reaction via decarbonylation, yielding a variety of tetrasubstituted alkenylsilanes in moderate to good yields.
Preparation method of NHC-PdCl2-3-chloropyridine complex
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Paragraph 0029-0032; 0041-0042; 0043-0044; 0045-0046, (2021/05/08)
The invention relates to a preparation method of an NHC-PdCl2-3-chloropyridine complex. The preparation method comprises the following steps: subjecting 2,6-diisopropylaniline, glyoxal and acetic acid to reacting in an ethanol solvent for 2-4 days to obtain glyoxal-bis-(2,6-diisopropylphenyl)imine; stirring a mixed solution of glyoxal-bis-(2,6-diisopropylphenyl)imine, chloromethylethyl ether, tetrahydrofuran and water at 30-50 DEG C for a reaction for 10-20 hours to obtain 1,3-bis-(2,6-diisopropylphenyl)imidazolium chloride, wherein a molar ratio of glyoxal-bis-(2,6-diisopropylphenyl)imine to water is 1: (2-10); and subjecting 1,3-bis-(2,6-diisopropylphenyl)imidazolium chloride, palladium chloride, cesium carbonate and 3-chloropyridine to reacting for 10-20 hours at a temperature of 60-100 DEG C to obtain [1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene](3-chloropyridyl)palladium (II) dichloride. The method has the advantages that raw materials are easy to obtain, operation is simple, reaction conditions are mild and easy to control and industrial mass production is easy.
Steric effect of NHC ligands in Pd(II)–NHC-catalyzed non-directed C–H acetoxylation of simple arenes
Mandal, Tanmoy,Yadav, Sudha,Choudhury, Joyanta
, (2021/09/06)
Although there has been a lot of progress in oxidative arene C–H functionalization reactions catalyzed by Pd(II/IV) system, the non-directed, site-selective functionalization of arene molecules is still challenging. It has been established that ligands play a pivotal role in controlling rate- as well as selectivity-determining step in a catalytic cycle involving well-defined metal-ligand bonding. N-heterocyclic carbene (NHC) ligands have had a tremendous contribution in the recent extraordinary success of achieving high reactivity and excellent selectivity in many catalytic processes including cross-coupling and olefin-metathesis reactions. However, the immense potential of these NHC ligands in improving site-selectivity of non-directed catalytic C–H functionalization reactions of simple arenes is yet to be realized, where overriding the electronic bias on deciding selectivity is a burdensome task. The presented work demonstrated an initiative step in this regard. Herein, a series of well-defined discrete [Pd(NHCR′R)(py)I2] complexes with systematically varied degree of spatial congestion at the Pd centre, exerted through the R and R’ substituents on the NHC ligand, were explored in controlling the activity as well as the site-selectivity of non-directed acetoxylation of representative monosubstituted and disubstituted simple arenes (such as toluene, iodobenzene and bromobenzene, naphthalene and 1,2-dichlorobenzene). The resulting best yields were found to be 75% for toluene and 65% for bromobenzene with [Pd(NHCMePh)(py)I2], 75% for iodobenzene and 79% for naphthalene with [Pd(NHCMeMe)(py)I2], and 41% for 1,2-dichlorobenzene with [Pd(NHCCyCy)(py)I2]. Most importantly, with increasing the bulkiness of the NHC ligand in the complexes, the selectivity of the distal C-acetoxylated products in comparison to the proximal ones, was enhanced to a great extent in all cases. Considering the vast library of NHC ligands, this study underscores the future opportunity to develop more strategies to improve the activity and the crucial site-selectivity of C–H functionalization reactions in simple as well as complex organic molecules.