42134-71-4Relevant academic research and scientific papers
Photochemical Organocatalytic Benzylation of Allylic C–H Bonds
Le Saux, Emilien,Melchiorre, Paolo,Zanini, Margherita
supporting information, p. 1113 - 1118 (2022/02/05)
We report a radical-based organocatalytic method for the direct benzylation of allylic C–H bonds. The process uses nonfunctionalized allylic substrates and readily available benzyl radical precursors and is driven by visible light. Crucial was the identification of a dithiophosphoric acid that performs two distinct catalytic roles, sequentially acting as a catalytic donor for the formation of photoactive electron donor–acceptor (EDA) complexes and then as a hydrogen atom abstractor. By mastering these orthogonal radical generation paths, the organic catalyst enables the formation of benzylic and allylic radicals, respectively, to then govern their selective coupling. The protocol was also used to design a three-component radical process, which increased the synthetic potential of the chemistry.
Iron-Based Catalyst for Borylation of Unactivated Alkyl Halides without Using Highly Basic Organometallic Reagents
Siddiqui, Sheema,Bhawar, Ramesh,Geetharani
supporting information, p. 1948 - 1954 (2021/01/14)
The mild borylation of alkyl bromides and chlorides with bis(neopentylglycolato)diborane (B2neop2) mediated by iron-bis amide is described. The reaction proceeds with a broad substrate scope and good functional group compatibility. Moreover, sufficient ca
Copper-catalyzed sp3-sp3 cross-coupling of turbo grignards with benzyl halides
Elahi-Mohassel, Synah,Girgis, Michael,Paige, Mikell,Petruncio, Greg
supporting information, (2021/11/17)
The aromatic ring in benzyl halides and sulfonates imparts unique reactivity at the benzylic carbon atom. Photoredox sp3-sp3 cross-coupling proved ineffective for coupling p-methoxybenzyl chloride (PMBCl), leading to a new strategy for the sp3-sp3 cross-coupling of benzyl halides and sulfonates. This strategy involved LiCl-accelerated synthesis of a Grignard reagent followed by a copper-catalyzed cross-coupling. The conditions worked well for PMBCl due to its exceptional reactivity but other benzyl bromides or sulfonates reacted poorly.
Synthesis of Dibenzyls by Nickel-Catalyzed Homocoupling of Benzyl Alcohols
Pan, Feng-Feng,Guo, Peng,Huang, Xiaochuang,Shu, Xing-Zhong
, p. 3094 - 3100 (2021/04/23)
Dibenzyls are essential building blocks that are widely used in organic synthesis, and they are typically prepared by the homocoupling of halides, organometallics, and ethers. Herein, we report an approach to this class of compounds using alcohols, which are more stable and readily available. The reaction proceeds via nickel-catalyzed and dimethyl oxalate assisted dynamic kinetic homocoupling of benzyl alcohols. Both primary and secondary alcohols are tolerated.
Use of Isopropyl Alcohol as a Reductant for Catalytic Dehydoxylative Dimerization of Benzylic Alcohols Utilizing Ti?O Bond Photohomolysis
Iwasawa, Nobuharu,Sumiyama, Keiichi,Toriumi, Naoyuki
supporting information, p. 2474 - 2478 (2021/06/25)
Photohomolysis of Ti?O bonds is utilized in photocatalytic generation of titanium(III) species for dehydroxylative dimerization of benzylic alcohols under UV-light irradiation by using isopropyl alcohol (IPA) as a stoichiometric reductant. In this reaction, IPA works not as a single-electron donor as in the photo-redox catalyzed reactions but as an H-atom-donor. The reaction also proceeds under visible-light irradiation in the presence of thioglycolic acid as a ligand.
Photo-catalytic preparation method of bibenzyl compounds
-
Paragraph 0049-0054; 0068-0071, (2020/02/27)
The invention relates to a preparation method of bibenzyl compounds. A compound represented by a formula (A) and a compound represented by a formula (C) carry out reactions under the action of an organic tungsten catalyst and an alkali in the presence of light to generate bibenzyl compounds represented by the formula (B). The method is simple and is easy to operate. The yield is high, and the application range is wide. Moreover, the invention also provides an application of a tungsten complex in organic chemical reactions as a photocatalyst.
Ni-Catalyzed Iterative Alkyl Transfer from Nitrogen Enabled by the in Situ Methylation of Tertiary Amines
Nwachukwu, Chideraa Iheanyi,McFadden, Timothy Patrick,Roberts, Andrew George
, p. 9979 - 9992 (2020/09/03)
Current methods to achieve transition-metal-catalyzed alkyl carbon-nitrogen (C-N) bond cleavage require the preformation of ammonium, pyridinium, or sulfonamide derivatives from the corresponding alkyl amines. These activated substrates permit C-N bond cleavage, and their resultant intermediates can be intercepted to affect carbon-carbon bond-forming transforms. Here, we report the combination of in situ amine methylation and Ni-catalyzed benzalkyl C-N bond cleavage under reductive conditions. This method permits iterative alkyl group transfer from tertiary amines and demonstrates a deaminative strategy for the construction of Csp3-Csp3 bonds. We demonstrate PO(OMe)3 (trimethylphosphate) to be a Ni-compatible methylation reagent for the in situ conversion of trialkyl amines into tetraalkylammonium salts. Single, double, and triple benzalkyl group transfers can all be achieved from the appropriately substituted tertiary amines. Transformations developed herein proceed via recurring events: The in situ methylation of tertiary amines by PO(OMe)3, Ni-catalyzed C-N bond cleavage, and concurrent Csp3-Csp3 bond formation.
Luminescent tungsten(vi) complexes as photocatalysts for light-driven C-C and C-B bond formation reactions
Chan, Kaai-Tung,Che, Chi-Ming,Du, Lili,Liu, Yungen,Phillips, David Lee,To, Wai-Pong,Tong, Glenna So Ming,Wu, Liang-Liang,Yu, Daohong
, p. 6370 - 6382 (2020/07/15)
The realization of photocatalysis for practical synthetic application hinges on the development of inexpensive photocatalysts which can be prepared on a large scale. Herein an air-stable, visible-light-absorbing photoluminescent tungsten(vi) complex which can be conveniently prepared at the gram-scale is described. This complex could catalyse photochemical organic transformation reactions including borylation of aryl halides, such as aryl chloride, reductive coupling of benzyl bromides for C-C bond formation, reductive coupling of phenacyl bromides, and decarboxylative coupling of redox-active esters of alkyl carboxylic acid with high product yields and broad functional group tolerance.
Photochemical Reductive C–C Coupling with a Guanidine Electron Donor
Wiesner, Sven,Walter, Petra,Wagner, Arne,Kaifer, Elisabeth,Himmel, Hans-J?rg
, p. 5045 - 5054 (2016/10/26)
The metal-free photoinduced reductive C–C coupling reactions of a number of substituted benzyl halides (15 examples) with the organic electron-donor 2,3,5,6-tetrakis(tetramethylguanidino)pyridine are evaluated. Depending on the substituents at the benzyl group, a C–C coupling product yield in the range 50–95 % is achieved. The photochemical benzyl-radical formation by homolytic N–C bond cleavage of the initially formed benzyl-pyridinium salts is the rate-determining step of these reactions. Electron-withdrawing as well as -donating substituents at the phenyl group increase the reaction rate. Quantum chemical computations did not reveal any correlation between either the enthalpy or Gibbs free energy of the N–C bond cleavage step and the experimentally determined first-order rate constants. Instead, the structural difference between the excited state generated by irradiation and the electronic ground state of the pyridinium ions could be used to rationalize the differences in the reaction rates.
Mechanism and Applications of the Photoredox Catalytic Coupling of Benzyl Bromides
Park, Gyurim,Yi, Seung Yeon,Jung, Jaehun,Cho, Eun Jin,You, Youngmin
, p. 17790 - 17799 (2016/11/28)
The photoredox catalytic coupling of halomethyl arenes to bibenzyl derivatives has been demonstrated. The catalytic protocol employed the Hantzsch ester, potassium phosphate, and a photoactive cyclometalated IrIIIcomplex catalyst. A photochemical quantum yield as high as 20 % was obtained. The catalytic mechanism was investigated in detail by performing photophysical and electrochemical measurements, as well as by quantum chemical calculations. The results suggest that two-electron mediation might be responsible for the improved photon economy. The reaction protocol was compatible with halomethyl arenes that contain a variety of functional groups. Finally, the synthetic utility of our protocol was demonstrated by the preparation of a natural dihydrostilbenoid, brittonin A.
