125847-21-4Relevant articles and documents
Enantioselective β-C(sp3)-H arylation of amides: Via synergistic nickel and photoredox catalysis
Cheng, Buqing,Huan, Leitao,Huo, Haohua,Shu, Xiaomin,Zhang, Wu
supporting information, p. 9407 - 9409 (2021/11/17)
An enantioselective benzylic β-C(sp3)-H arylation of amides via synergistic nickel and photoredox catalysis is reported. The C-H bond is activated by a bromine-radical-mediated C-H cleavage. This mild yet straightforward protocol provides arylation products in up to 96% yield and with up to 95% ee. This journal is
Reductive activation and hydrofunctionalization of olefins by multiphoton tandem photoredox catalysis
Czyz, Milena L.,Taylor, Mitchell S.,Horngren, Tyra H.,Polyzos, Anastasios
, p. 5472 - 5480 (2021/06/01)
The conversion of olefin feedstocks to architecturally complex alkanes represents an important strategy in the expedient generation of valuable molecules for the chemical and life sciences. Synthetic approaches are reliant on the electrophilic activation of unactivated olefins, necessitating functionalization with nucleophiles. However, the reductive functionalization of unactivated and less activated olefins with electrophiles remains an ongoing challenge in synthetic chemistry. Here, we report the nucleophilic activation of inert styrenes through a photoinduced direct single electron reduction to the corresponding nucleophilic radical anion. Central to this approach is the multiphoton tandem photoredox cycle of the iridium photocatalyst [Ir(ppy)2(dtbbpy)] PF6, which triggers in situ formation of a high-energy photoreductant that selectively reduces styrene olefinic π bonds to radical anions without stoichiometric reductants or dissolving metals. This mild strategy enables the chemoselective reduction and hydrofunctionalization of styrenes to furnish valuable alkane and tertiary alcohol derivatives. Mechanistic studies support the formation of a styrene olefinic radical anion intermediate and a Birch-type reduction involving two sequential single electron transfers. Overall, this complementary mode of olefin activation achieves the hydrofunctionalization of less activated alkenes with electrophiles, adding value to abundant olefins as valuable building blocks in modern synthetic protocols.
Copper-Catalyzed Enantioconvergent Radical Suzuki-Miyaura C(sp3)-C(sp2) Cross-Coupling
Jiang, Sheng-Peng,Dong, Xiao-Yang,Gu, Qiang-Shuai,Ye, Liu,Li, Zhong-Liang,Liu, Xin-Yuan
supporting information, p. 19652 - 19659 (2020/12/01)
A copper-catalyzed enantioconvergent Suzuki-Miyaura C(sp3)-C(sp2) cross-coupling of various racemic alkyl halides with organoboronate esters has been established in high enantioselectivity. Critical to the success is the use of a chiral cinchona alkaloid-derived N,N,P-ligand for not only enhancing the reducing capability of copper catalyst to favor a stereoablative radical pathway over a stereospecific SN2-type process but also providing an ideal chiral environment to achieve the challenging enantiocontrol over the highly reactive radical species. The reaction has a broad scope with respect to both coupling partners, covering aryl- and heteroarylboronate esters, as well as benzyl-, heterobenzyl-, and propargyl bromides and chlorides with good functional group compatibility. Thus, it provides expedient access toward a range of useful enantioenriched skeletons featuring chiral tertiary benzylic stereocenters.
Nickel-Catalyzed Electrochemical Reductive Relay Cross-Coupling of Alkyl Halides to Aryl Halides
Fang, Ping,Jiao, Ke-Jin,Liu, Dong,Ma, Hong-Xing,Mei, Tian-Sheng,Qiu, Hui
supporting information, p. 6520 - 6524 (2020/01/24)
A highly regioselective Ni-catalyzed electrochemical reductive relay cross-coupling between an aryl halide and an alkyl halide has been developed in an undivided cell. Various functional groups are tolerated under these mild reaction conditions, which pro
Photo-Ni-Dual-Catalytic C(sp2)-C(sp3) Cross-Coupling Reactions with Mesoporous Graphitic Carbon Nitride as a Heterogeneous Organic Semiconductor Photocatalyst
Antonietti, Markus,Ghosh, Indrajit,K?nig, Burkhard,Khamrai, Jagadish,Savateev, Aleksandr
, p. 3526 - 3532 (2020/04/09)
The synergistic combination of a heterogeneous organic semiconductor mesoporous graphitic carbon nitride (mpg-CN) and a homogeneous nickel catalyst with visible-light irradiation at room temperature affords the C(sp2)-C(sp3) cross-co
Visible-light-mediated external-reductant-free reductive cross coupling of benzylammonium salts with (hetero)aryl nitriles
Miao, Meng,Liao, Li-Li,Cao, Guang-Mei,Zhou, Wen-Jun,Yu, Da-Gang
, p. 1519 - 1524 (2019/11/03)
Herein we report a novel visible-light-mediated external reductant-free reductive cross coupling for the construction of C sp2–C sp3 bonds. A variety of benzylammonium salts underwent selective coupling with (hetero)aryl nitriles to
Nickel-Catalyzed Reductive Cross-Coupling of Benzyl Halides with Aryl Halides
Zhang, Qingchen,Wang, Xuan,Qian, Qun,Gong, Hegui
supporting information, p. 2829 - 2836 (2016/08/31)
Systematic studies of the coupling of benzylic with aryl halides are presented. The optimized reaction conditions for electron-deficient aryl halides cannot be applied to the electron-rich or neutral counterparts, and vice versa. The excellent functional group tolerance and broad substrate scope may enable the current work to be useful for the construction of diaryl methane products.
Visible-Light-Mediated Aromatic Substitution Reactions of Cyanoarenes with 4-Alkyl-1,4-dihydropyridines through Double Carbon-Carbon Bond Cleavage
Nakajima, Kazunari,Nojima, Sunao,Sakata, Ken,Nishibayashi, Yoshiaki
, p. 1028 - 1032 (2016/04/05)
Novel aromatic substitution reactions of cyanoarenes with 4-alkyl-1,4-dihydropyridines as alkylating reagents in the presence of a catalytic amount of a photoredox catalyst proceed smoothly to give the corresponding alkyl-substituted arenes in good to high yields. The present reaction system realizes a novel C-C bond-forming reaction between two fragments generated from the C-C bond-cleavage reactions of two independent substrates.
Nickel-catalyzed cross-coupling of photoredox-generated radicals: Uncovering a general manifold for stereoconvergence in nickel-catalyzed cross-couplings
Gutierrez, Osvaldo,Tellis, John C.,Primer, David N.,Molander, Gary A.,Kozlowski, Marisa C.
supporting information, p. 4896 - 4899 (2015/05/05)
The cross-coupling of sp3-hybridized organoboron reagents via photoredox/nickel dual catalysis represents a new paradigm of reactivity for engaging alkylmetallic reagents in transition-metal-catalyzed processes. Reported here is an investigation into the mechanistic details of this important transformation using density functional theory. Calculations bring to light a new reaction pathway involving an alkylnickel(I) complex generated by addition of an alkyl radical to Ni(0) that is likely to operate simultaneously with the previously proposed mechanism. Analysis of the enantioselective variant of the transformation reveals an unexpected manifold for stereoinduction involving dynamic kinetic resolution (DKR) of a Ni(III) intermediate wherein the stereodetermining step is reductive elimination. Furthermore, calculations suggest that the DKR-based stereoinduction manifold may be responsible for stereoselectivity observed in numerous other stereoconvergent Ni-catalyzed cross-couplings and reductive couplings.
The direct arylation of allylic sp3 C-H bonds via organic and photoredox catalysis
Cuthbertson, James D.,MacMillan, David W. C.
, p. 74 - 77 (2015/03/18)
The direct functionalization of unactivated sp3 C-H bonds is still one of the most challenging problems facing synthetic organic chemists. The appeal of such transformations derives from their capacity to facilitate the construction of complex organic molecules via the coupling of simple and otherwise inert building blocks, without introducing extraneous functional groups. Despite notable recent efforts, the establishment of general and mild strategies for the engagement of sp3 C-H bonds in C-C bond forming reactions has proved difficult. Within this context, the discovery of chemical transformations that are able to directly functionalize allylic methyl, methylene and methine carbons in a catalytic manner is a priority. Although protocols for direct oxidation and amination of allylic C-H bonds (that is, C-H bonds where an adjacent carbon is involved in a C = C bond) have become widely established, the engagement of allylic substrates in C-C bond forming reactions has thus far required the use of pre-functionalized coupling partners. In particular, the direct arylation of non-functionalized allylic systems would enable access to a series of known pharmacophores (molecular features responsible for a drug's action), though a general solution to this long-standing challenge remains elusive. Here we report the use of both photoredox and organic catalysis to accomplish a mild, broadly effective direct allylic C-H arylation. This C-C bond forming reaction readily accommodates a broad range of alkene and electron-deficient arene reactants, and has been used in the direct arylation of benzylic C-H bonds.
