21969-45-9Relevant articles and documents
A novel Suzuki-type cross-coupling reaction of cyclopropylboronic esters with benzyl bromides
Chen, Han,Deng, Min-Zhi
, p. 1609 - 1613 (2000)
The Suzuki-type coupling reaction of cyclopropylboronic acids (esters) with benzyl bromides readily takes place by using Ag2O with KOH as the base. The reaction rate and the cross-coupling product yields of cyclopropylboronate esters of ethylene glycol or propane-1,3-diol were higher and better than those of cyclopropylboronic acids. However, the coupling reaction of the cyclopropylboronate esters of glycol with larger substituents was sluggish. The highly optically active benzyl-substituted cyclopropanes could be obtained by the coupling reactions of corresponding optically active cyclopropylboronate esters with benzyl bromides. A novel, ideal method for preparing stereo-defined benzyl-substituted cyclopropanes, especially optically active benzyl-substituted cyclopropanes, is described here.
Direct gem-difluoromethylenation of sp3-hybridized carbon center through copper-mediated radical/radical cross-coupling for the construction of a CH2-CF2 linkage
Jiang, Haizhen,Xu, Minjun,Lu, Wenjun,Tian, Wenfeng,Wan, Wen,Chen, Yunrong,Deng, Hongmei,Wu, Shaoxiong,Hao, Jian
, p. 15756 - 15759 (2015)
Efficient direct gem-difluoromethylenation of an sp3-hybridized carbon center in benzyl bromides using benzo-1,3-azolic (oxa-, thia- or aza-) difluoromethyl bromides for construction of a CH2-CF2 linkage has been developed through radical/radical C-C cross-coupling via two separate single electron transfer processes (SET) under the promotion of different copper sources.
Photolysis of naphtho[b]cyclopropene. Detection of a diradical intermediate
Pan, Weitao,Jones Jr., Maitland,Esat, Burak,Lahti, Paul M.
, p. 1505 - 1508 (1998)
Photolysis of naphtho[b]cyclopropene in hydrocarbons leads to products derived from hydrogen abstraction by a diradical. Photolysis in a cryogenic matrix allows ESR detection of this diradical, which has zero field splitting parameters D/hc = 0.057, E/hc -1.
One-Shot Radical Cross Coupling Between Benzyl Alcohols and Alkenyl Halides Using Ni/Ti/Mn System
Suga, Takuya,Takahashi, Yuuki,Ukaji, Yutaka
supporting information, p. 5622 - 5626 (2020/10/22)
A “one-shot” cross coupling between benzyl alcohols and alkenyl halides has been established. A combination of low-valent Ti-mediated C?OH homolysis and the prominent chemistry of Ni-based radical catalysis afforded the desired cross-coupled product with good efficiency. The reaction proceeded regardless of the electronic property of benzyl alcohols, and Ar?B bond remained intact throughout the reaction. Alkenyl bromides with various substitution patterns were applicable to this reaction. Attempts for utilizing sterically demanding tri-substituted alkenes indicated that the steric hinderance mainly inhibited the radical-trapping by Ni species. This reaction can be a simple and efficient strategy for synthesizing densely substituted allylbenzene derivatives. (Figure presented.).
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.
Nickel-Catalyzed Amination of α-Aryl Methyl Ethers
Patel, Purvish,Rousseaux, Sophie A. L.
, p. 492 - 496 (2020/03/13)
α-Aryl amines are prevalent in pharmaceutically active compounds and natural products. Herein, we describe a Ni-catalyzed protocol for their synthesis from readily available α-aryl ethers. While α-aryl ethers have been used as electrophiles in Ni-catalyzed C-C bond formations, their use in C-heteroatom bond formation is much less prevalent. Preliminary mechanistic insight suggests that oxidative addition is facilitated by an anionic ligand and that reductive elimination is a reversible process.
Reductive coupling of benzyl oxalates with highly functionalized alkyl bromides by nickel catalysis
Yan, Xiao-Biao,Li, Chun-Ling,Jin, Wen-Jie,Guo, Peng,Shu, Xing-Zhong
, p. 4529 - 4534 (2018/05/28)
Coupling reactions involving non-sulfonated C-O electrophiles provide a promising method for forming C-C bonds, but the incorporation of functionalized or secondary alkyl groups remains a challenge due to the requirement for well-defined alkylmetal specie
Low-Valent Titanium-Mediated Radical Conjugate Addition Using Benzyl Alcohols as Benzyl Radical Sources
Suga, Takuya,Shimazu, Shoma,Ukaji, Yutaka
, p. 5389 - 5392 (2018/09/12)
A concise method to directly generate benzyl radicals from benzyl alcohol derivatives has been developed. The simple and inexpensive combination of TiCl4(collidine) (collidine = 2,4,6-collidine) and manganese powder afforded a low-valent titanium reagent, which facilitated homolytic cleavage of benzylic C-OH bonds. The application to radical conjugate addition reactions demonstrated the broad scope of this method. The reaction of various benzyl alcohol derivatives with electron-deficient alkenes furnished the corresponding radical adducts.
Intra- and Intermolecular Nickel-Catalyzed Reductive Cross-Electrophile Coupling Reactions of Benzylic Esters with Aryl Halides
Konev, Mikhail O.,Hanna, Luke E.,Jarvo, Elizabeth R.
supporting information, p. 6730 - 6733 (2016/06/09)
Nickel-catalyzed cross-electrophile coupling reactions of benzylic esters and aryl halides have been developed. Both inter- and intramolecular variants proceed under mild reaction conditions. A range of heterocycles and functional groups are tolerated under the reaction conditions. Additionally, the first example of a stereospecific cross-electrophile coupling of a secondary benzylic ester is described. Crossed off: Nickel-catalyzed cross-electrophile coupling reactions of benzylic esters and aryl halides have been developed. Both inter- and intramolecular variants proceed under mild reaction conditions, and a range of heterocycles and functional groups are tolerated. Additionally, the first example of a stereospecific cross-electrophile coupling of a secondary benzylic ester is described.
A clean and selective radical homocoupling employing carboxylic acids with titania photoredox catalysis
Manley, David W.,Walton, John C.
supporting information, p. 5394 - 5397 (2015/02/19)
A titania photoredox catalysis protocol was developed for the homocoupling of C-centered radicals derived from carboxylic acids. Intermolecular reactions were generally efficient and selective, furnishing the desired dimers in good yields under mild neutral conditions. Selective cross-coupling with two acids proved unsuccessful. An intra-molecular adaptation enabled macrocycles to be prepared, albeit in modest yields. (Chemical Equation Presented).
