1667-11-4Relevant articles and documents
Multiple-photon ? chemistry in the laser-jet: Photochemistry of the 4-biphenylmethyl radical
Adam, Waldemar,Schneider, Katrin
, p. 441 - 444 (1997)
In laser-jet (LJ) photolysis (high intensity) of the ether 4-(4-benzoylphenoxymethyl)biphenyl 1 a two-photon process is observed in CCl4 to yield 4-(chloromethyl)biphenyl 5 as product (3%), while the one-photon product is 4-biphenylaldehyde 7 (100% in conventional photolysis versus 97% in laser-jet photolysis). In ethanol, the results suggest a three-proton reaction in which 4-(ethoxymethyl)biphenyl 6 is produced in appreciable amounts (18%) in addition to the one-photon product 1,2-bis(4-biphenyl)ethane 4, the latter as the major product (82%). It is proposed that under high-intensity LJ photolysis conditions the electronically-excited 4-biphenylmethyl radical 2* is photoionized to the 4-biphenylmethyl cation 2+ and that the latter is trapped by ethanol to give the 4-biphenylmethyl ether 6.
Palladium-anchored multidentate SBA-15/di-urea nanoreactor: A highly active catalyst for Suzuki coupling reaction
Rohani, Sahar,Mohammadi Ziarani, Ghodsi,Badiei, Alireza,Ziarati, Abolfazl,Jafari, Maryam,Shayesteh, Alireza
, (2018)
Modification of mesoporous silica was carried out by reaction of SBA-15 with di-urea-based ligand. Next, with the help of this ligand, palladium ions were anchored within the multidentate SBA-15/di-urea pore channels with high dispersion. The SBA-15/di-urea/Pd catalyst was characterized using various techniques. Theoretical calculations indicated that each palladium ion was strongly interacted with one nitrogen and two oxygen atoms from the multidentate di-urea ligand located in SBA-15 channels and these interactions remained during the catalytic cycle. These results are in good agreement with those of hot filtration test: the palladium ions have very high stability against leaching from the SBA-15/di-urea support. The catalytic performance of SBA-15/di-urea/Pd nanostructure was examined for the Suzuki coupling reaction of phenylboronic acid and electronically diverse aryl halides under mild conditions with a minimal amount of Pd (0.26?mol%). Compared to previous reports, this protocol afforded some advantages such as short reaction times, high yields of products, catalyst stability without leaching, easy catalyst recovery and preservation of catalytic activity for at least six successive runs.
Mechanism of solvolysis of substituted benzyl chlorides in aqueous ethanol
Denegri, Bernard,Mati?, Mirela,Va?ko, Monika
supporting information, (2021/11/22)
The mechanism of solvolyses of activated ortho-, meta- and para-substituted benzyl chlorides in aqueous ethanol has been studied by using the Hammett-Brown and Yukawa-Tsuno treatments as well as by correlating logarithms of solvolysis rate constants with relative stabilities of corresponding benzyl carbocations in water calculated at the IEFPCM-M06–2X/6-311+G(3df,3pd) level of theory. Benzyl chlorides containing strong conjugative electron-donors in the para-position solvolyze by the SN1 mechanism, whereas other activated benzyl chlorides solvolyze by the SN2 mechanism via loose transition states.
Palladium-catalyzed carbonylative cyclization of benzyl chlorides with anthranils for the synthesis of 3-arylquinolin-2(1: H)-ones
Liu, Jian-Li,Xu, Ren-Rui,Wang, Wei,Qi, Xinxin,Wu, Xiao-Feng
supporting information, p. 3584 - 3588 (2021/05/04)
An efficient carbonylative procedure for the synthesis of 3-arylquinoin-2(1H)-ones has been established. Through a palladium-catalyzed aminocarbonylation of benzyl chlorides with anthranils, a variety of 3-arylquinoin-2(1H)-one products were obtained in moderate to excellent yields with good functional group tolerance. This journal is
Synthesis and evaluation of tetrahydroisoquinoline derivatives against Trypanosoma brucei rhodesiense
Cullen, Danica R.,Gallagher, Ashlee,Duncan, Caitlin L.,Pengon, Jutharat,Rattanajak, Roonglawan,Chaplin, Jason,Gunosewoyo, Hendra,Kamchonwongpaisan, Sumalee,Payne, Alan,Mocerino, Mauro
, (2021/10/07)
Human African Trypanosomiasis (HAT) is a neglected tropical disease caused by the parasitic protozoan Trypanosoma brucei (T. b.), and affects communities in sub-Saharan Africa. Previously, analogues of a tetrahydroisoquinoline scaffold were reported as having in vitro activity (IC50 = 0.25–70.5 μM) against T. b. rhodesiense. In this study the synthesis and antitrypanosomal activity of 80 compounds based around a core tetrahydroisoquinoline scaffold are reported. A detailed structure activity relationship was revealed, and five derivatives (two of which have been previously reported) with inhibition of T. b. rhodesiense growth in the sub-micromolar range were identified. Four of these (3c, 12b, 17b and 26a) were also found to have good selectivity over mammalian cells (SI > 50). Calculated logD values and preliminary ADME studies predict that these compounds are likely to have good absorption and metabolic stability, with the ability to passively permeate the blood brain barrier. This makes them excellent leads for a blood-brain barrier permeable antitrypanosomal scaffold.
Nickel-Catalyzed Asymmetric Reductive Arylbenzylation of Unactivated Alkenes
Jin, Youxiang,Yang, Haobo,Wang, Chuan
, p. 2724 - 2729 (2020/04/02)
Herein, we report a nickel-catalyzed asymmetric two-component reductive dicarbofunctionalization of aryl iodide-tethered unactivated alkenes using benzyl chlorides as the challenging coupling partner. This arylbenzylation reaction enables the efficient synthesis of diverse benzene-fused cyclic compounds bearing a quaternary stereocenter with a high tolerance of sensitive functionalities in highly enantioselective manner. The preliminary mechanistic investigations suggest a radical chain reaction mechanism.
Visible Light-Catalyzed Benzylic C-H Bond Chlorination by a Combination of Organic Dye (Acr+-Mes) and N-Chlorosuccinimide
Xiang, Ming,Zhou, Chao,Yang, Xiu-Long,Chen, Bin,Tung, Chen-Ho,Wu, Li-Zhu
, p. 9080 - 9087 (2020/08/14)
By combining "N-chlorosuccinimide (NCS)"as the safe chlorine source with "Acr+-Mes"as the photocatalyst, we successfully achieved benzylic C-H bond chlorination under visible light irradiation. Furthermore, benzylic chlorides could be converted to benzylic ethers smoothly in a one-pot manner by adding sodium methoxide. This mild and scalable chlorination method worked effectively for diverse toluene derivatives, especially for electron-deficient substrates. Careful mechanistic studies supported that NCS provided a hydrogen abstractor "N-centered succinimidyl radical,"which was responsible for the cleavage of the benzylic C-H bond, relying on the reducing ability of Acr?-Mes.
Biphenyl acetic acid and preparation method thereof
-
Paragraph 0012; 0030; 0033; 0036; 0039; 0042; 0045; 0058, (2020/09/09)
The invention discloses biphenyl acetic acid and a preparation method thereof. The preparation method comprises the following steps: dissolving bromobenzene into dimethylformamide, and performing reaction under the action of palladium powder to obtain biphenyl; dissolving biphenyl in cyclohexane, and performing chloromethylation reaction on biphenyl in a hydrochloric acid solution and a saturatedformaldehyde aqueous solution to obtain an intermediate 1; dissolving sodium cyanide in deionized water, and performing cyanidation reaction on the intermediate 1 and a sodium cyanide aqueous solutionunder the action of a catalyst n-butylammonium bromide to obtain an intermediate 2; and further hydrolyzing the intermediate 2 under the condition of an alkaline aqueous solution, and performing acidifying under the action of hydrochloric acid to obtain biphenyl acetic acid. The yield of the biphenyl acetic acid prepared by the aid of the method is higher than that of the biphenyl acetic acid prepared by the aid of traditional processes, reactants are low in price, the preparation cost of the biphenyl acetic acid can be greatly reduced, and the method is favorable for market popularization.
Operando Spectroscopic and Kinetic Characterization of Aerobic Allylic C-H Acetoxylation Catalyzed by Pd(OAc)2/4,5-Diazafluoren-9-one
Jaworski, Jonathan N.,Kozack, Caitlin V.,Tereniak, Stephen J.,Knapp, Spring Melody M.,Landis, Clark R.,Miller, Jeffrey T.,Stahl, Shannon S.
supporting information, p. 10462 - 10474 (2019/07/09)
Allylic C-H acetoxylations are among the most widely studied palladium(II)-catalyzed C-H oxidation reactions. While the principal reaction steps are well established, key features of the catalytic mechanisms are poorly characterized, including the identity of the turnover-limiting step and the catalyst resting state. Here, we report a mechanistic study of aerobic allylic acetoxylation of allylbenzene with a catalyst system composed of Pd(OAc)2 and 4,5-diazafluoren-9-one (DAF). The DAF ligand is unique in its ability to support aerobic catalytic turnover, even in the absence of benzoquinone or other co-catalysts. Herein, we describe operando spectroscopic analysis of the catalytic reaction using X-ray absorption and NMR spectroscopic methods that allow direct observation of the formation and decay of a palladium(I) species during the reaction. Kinetic studies reveal the presence of two distinct kinetic phases: (1) a burst phase, involving rapid formation of the allylic acetoxylation product and formation of the dimeric PdI complex [PdI(DAF)(OAc)]2, followed by (2) a post-burst phase that coincides with evolution of the catalyst resting state from the PdI dimer into a π-allyl-PdII species. The data provide unprecedented insights into the role of ancillary ligands in supporting catalytic turnover with O2 as the stoichiometric oxidant and establish an important foundation for the development of improved catalysts for allylic oxidation reactions.
α-Diimine-Niobium Complex-Catalyzed Deoxychlorination of Benzyl Ethers with Silicon Tetrachloride
Parker, Bernard F.,Hosoya, Hiromu,Arnold, John,Tsurugi, Hayato,Mashima, Kazushi
supporting information, p. 12825 - 12831 (2019/10/19)
α-Diimine niobium complexes serve as catalysts for deoxygenation of benzyl ethers by silicon tetrachloride (SiCl4) to cleanly give two equivalents of the corresponding benzyl chlorides, where SiCl4 has the dual function of oxygen scavenger and chloride source with the formation of a silyl ether or silica as the only byproduct. The reaction mechanism has two successive trans-etherification steps that are mediated by the niobium catalyst, first forming one equivalent of benzyl chloride along with the corresponding silyl ether intermediate that undergoes the same reaction pathway to give the second equivalent of benzyl chloride and silyl ether.