3842-58-8Relevant articles and documents
Dealkenylative Ni-Catalyzed Cross-Coupling Enabled by Tetrazine and Photoexcitation
Cao, Yuhui,Che, Jinteng,Chen, Han,Chen, Si-Cong,Fang, Xianhe,Guo, Yinliang,Guo, Zhixian,Kong, Lingran,Li, Chen,Lu, Jia-Tian,Luo, Tuoping,Zhang, Nan,Zhu, Qi
, p. 14046 - 14052 (2021/09/13)
A new and general method to functionalize the C(sp3)-C(sp2) bond of alkyl and alkene linkages has been developed, leading to the dealkenylative generation of carbon-centered radicals that can be intercepted to undergo Ni-catalyzed C(sp3)-C(sp2) cross-coupling. This one-pot protocol leverages the easily procured alkene feedstocks for organic synthesis with excellent functional group compatibility without the need for a photoredox catalyst.
Three-Component Alkene Difunctionalization by Direct and Selective Activation of Aliphatic C?H Bonds
Xu, Sheng,Chen, Herong,Zhou, Zhijun,Kong, Wangqing
supporting information, p. 7405 - 7411 (2021/02/20)
Catalytic alkene difunctionalization is a powerful strategy for the rapid assembly of complex molecules and has wide range of applications in synthetic chemistry. Despite significant progress, a compelling challenge that still needs to be solved is the installation of highly functionalized C(sp3)-hybridized centers without requiring pre-activated substrates. We herein report that inexpensive and easy-to-synthesize decatungstate photo-HAT, in combination with nickel catalysis, provides a versatile platform for three-component alkene difunctionalization through direct and selective activation of aliphatic C?H bonds. Compared with previous studies, the significant advantages of this strategy are that the most abundant hydrocarbons are used as feedstocks, and various highly functionalized tertiary, secondary, and primary C(sp3)-hybrid centers can be easily installed. The practicability of this strategy is demonstrated in the selective late-stage functionalization of natural products and the concise synthesis of pharmaceutically relevant molecules including Piragliatin.
Generation of Alkyl Radical through Direct Excitation of Boracene-Based Alkylborate
Hashizume, Daisuke,Hosoya, Takamitsu,Nakamura, Kei,Ohmiya, Hirohisa,Sato, Yukiya,Sumida, Yuto
supporting information, p. 9938 - 9943 (2020/06/27)
The generation of tertiary, secondary, and primary alkyl radicals has been achieved by the direct visible-light excitation of a boracene-based alkylborate. This system is based on the photophysical properties of the organoboron molecule. The protocol is applicable to decyanoalkylation, Giese addition, and nickel-catalyzed carbon-carbon bond formations such as alkyl-aryl cross-coupling or vicinal alkylarylation of alkenes, enabling the introduction of various C(sp3) fragments to organic molecules.
General C(sp2)-C(sp3) Cross-Electrophile Coupling Reactions Enabled by Overcharge Protection of Homogeneous Electrocatalysts
Hamby, Taylor B.,Sevov, Christo S.,Truesdell, Blaise L.
supporting information, p. 5884 - 5893 (2020/04/10)
Cross-electrophile coupling (XEC) of alkyl and aryl halides promoted by electrochemistry represents an attractive alternative to conventional methods that require stoichiometric quantities of high-energy reductants. Most importantly, electroreduction can readily exceed the reducing potentials of chemical reductants to activate catalysts with improved reactivities and selectivities over conventional systems. This work details the mechanistically-driven development of an electrochemical methodology for XEC that utilizes redox-active shuttles developed by the energy-storage community to protect reactive coupling catalysts from overreduction. The resulting electrocatalytic system is practical, scalable, and broadly applicable to the reductive coupling of a wide range of aryl, heteroaryl, or vinyl bromides with primary or secondary alkyl bromides. The impact of overcharge protection as a strategy for electrosynthetic methodologies is underscored by the dramatic differences in yields from coupling reactions with added redox shuttles (generally >80%) and those without (generally 20%). In addition to excellent yields for a wide range of substrates, reactions protected from overreduction can be performed at high currents and on multigram scales.
Boracene-based alkylborate enabled Ni/Ir hybrid catalysis
Hosoya, Takamitsu,Miyamoto, Yusuke,Ohmiya, Hirohisa,Sato, Yukiya,Sumida, Yuto
, p. 6598 - 6601 (2020/10/02)
Boracene-based alkylborate enabled visible light-mediated metallaphotoredox catalysis. The directly excited borate was easily oxidatively quenched by an excited Ir photoredox catalyst. Ni/Ir hybrid catalysis afforded the products under significantly low i
Visible-Light-Promoted Iron-Catalyzed C(sp2)–C(sp3) Kumada Cross-Coupling in Flow
Wei, Xiao-Jing,Abdiaj, Irini,Sambiagio, Carlo,Li, Chenfei,Zysman-Colman, Eli,Alcázar, Jesús,No?l, Timothy
supporting information, p. 13030 - 13034 (2019/07/18)
A continuous-flow, visible-light-promoted method has been developed to overcome the limitations of iron-catalyzed Kumada–Corriu cross-coupling reactions. A variety of strongly electron rich aryl chlorides, previously hardly reactive, could be efficiently coupled with aliphatic Grignard reagents at room temperature in high yields and within a few minutes’ residence time, considerably enhancing the applicability of this iron-catalyzed reaction. The robustness of this protocol was demonstrated on a multigram scale, thus providing the potential for future pharmaceutical application.
Nickel-catalyzed C-N bond activation: Activated primary amines as alkylating reagents in reductive cross-coupling
Yue, Huifeng,Zhu, Chen,Shen, Li,Geng, Qiuyang,Hock, Katharina J.,Yuan, Tingting,Cavallo, Luigi,Rueping, Magnus
, p. 4430 - 4435 (2019/04/29)
Nickel-catalyzed reductive cross coupling of activated primary amines with aryl halides under mild reaction conditions has been achieved for the first time. Due to the avoidance of stoichiometric organometallic reagents and external bases, the scope regarding both coupling partners is broad. Thus, a wide range of substrates, natural products and drugs with diverse functional groups are tolerated. Moreover, experimental mechanistic investigations and density functional theory (DFT) calculations in combination with wavefunction analysis have been performed to understand the catalytic cycle in more detail.
Iron-catalyzed cross coupling of aryl chlorides with alkyl Grignard reagents: Synthetic scope and FeII/FeIV mechanism supported by x-ray absorption spectroscopy and density functional theory calculations
Agata, Ryosuke,Takaya, Hikaru,Matsuda, Hiroshi,Nakatani, Naoki,Takeuchi, Katsuhiko,Iwamoto, Takahiro,Hatakeyama, Takuji,Nakamura, Masaharu
supporting information, p. 381 - 390 (2019/02/25)
A combination of iron(III) fluoride and 1,3-bis(2,6-diiso-propylphenyl)imidazolin-2-ylidene (SIPr) catalyzes the high-yielding cross coupling of an electron-rich aryl chloride with an alkyl Grignard reagent, which cannot be attained using other iron catalysts. A variety of alkoxy-or amino-substituted aryl chlorides can be cross-coupled with various alkyl Grignard reagents regardless of the presence or absence of β-hydrogens in the alkyl group. A radical probe experiment using 1-(but-3-enyl)-2-chlorobenzene does not afford the corresponding cyclization product, therefore excluding the intermediacy of radical species. Solution-phase X-ray absorption spectroscopy (XAS) analysis, with the help of density functional theory (DFT) calculations, indicates the formation of a high-spin (S = 2) heteroleptic difluorido organoferrate(II), [MgX][FeIIF2(SIPr)-(Me/alkyl)], in the reaction mixture. DFT calculations also support a feasible reaction pathway, including the formation of a difluorido organoferrate(II) intermediate which undergoes a novel Lewis acid-assisted oxidative addition to form a neutral organoiron(IV) intermediate, which leads to an FeII/FeIV cata-lytic cycle, where the fluorido ligand and the magnesium ion play key roles.
Purposeful regioselectivity control of the Birch reductive alkylation of biphenyl-4-carbonitrile
Fedyushin, Pavel A.,Peshkov, Roman Yu.,Panteleeva, Elena V.,Tretyakov, Evgeny V.,Beregovaya, Irina V.,Gatilov, Yuri V.,Shteingarts, Vitalij D.
, p. 842 - 851 (2018/01/19)
Birch's reductive alkylation of biphenyl-4-carbonitrile (1) provides alkylated 1,4-dihydroderivatives of various structural types: 4-alkyl-4-phenylcyclohexa-2,5-dienone, 1,4-dialkyl-4-phenylcyclohexa-2,5-dienecarbonitrile (with the same or different alkyl fragments), and 4-(1-alkylcyclohexa-2,5-dienyl)benzonitrile. Each of these products become dominant depending on the nature of long-living anionic form generated from 1, namely, the stable product of two-electrons reduction – dianion (12?); 1-alkyl-4-cyano-1-phenylcyclohexa-2,5-dien-4-yl anion (1-Alk1–), originated due to the alkylation of dianion 12? at the position 1 of biphenyl moiety; or 1-(4-cyanophenyl)cyclohexa-2,5-dien-1-yl anion (1-H4’–), being the product of dianion 12? protonation at position 4′ by protonating reagent (MeOH or NH4Cl). The orientation of alkyl fragment incorporation into biphenyl-4-carbonitrile scaffold is in agreement with calculated electronic structure of the anionic species under investigation. The dominating type of their reactivity towards alkyl halides proved to be nucleophilic (SN2 mechanism).
Nickel-Catalyzed Decarboxylative Alkylation of Aryl Iodides with Anhydrides
Chen, Hui,Hu, Lu,Ji, Wenzhi,Yao, Licheng,Liao, Xuebin
, p. 10479 - 10485 (2018/10/24)
We present the anhydride-based decarboxylative alkylation of aryl iodides catalyzed by nickel. This method of decarboxylative coupling works with a broad scope of aliphatic carboxylic anhydrides and tolerates synthetically useful aromatic substituents. Assisted by a redox system of pyridine N-oxide and zinc additives, the current reaction occurs under mild conditions and without the assistance of photocatalyst. Notably, this method features high chemoselectivity toward alkyl migration with mixed aliphatic/aromatic anhydrides. Thus, it provides a powerful synthetic tool to modify high-valued aliphatic carboxylic acids by converting them into mixed anhydrides using readily available aryl carboxylic acids such as p-toluic acid. We propose a catalytic cycle that involves the key steps of free radical-based decarboxylation and subsequent alkyl transfer to nickel that precedes an oxidatively induced C-C reductive elimination from Ni(III).
