2918-73-2Relevant academic research and scientific papers
Bromo Radical-Mediated Photoredox Aldehyde Decarbonylation towards Transition-Metal-Free Hydroalkylation of Acrylamides at Room Temperature
Sun, Zhaozhao,Huang, Huawen,Wang, Qiaolin,Deng, Guo-Jun
supporting information, p. 453 - 458 (2021/12/03)
Herein, we report a visible-light-mediated hydroalkylation reaction of alkenes using easily available aldehydes as alkyl sources via bromo radical-promoted photoredox decarbonylation. This protocol provides an alternative entry to C(sp3)?C(sp3) bond formation and features considerable advantages including mild and clean reaction conditions, obviation for transition-metal catalyst, and good functional group compatibility.
A benzene-bridged divanadium complex-early transition metal catalyst for alkene alkylarylation with PhI(O2CR)2viadecarboxylation
Zhang, Lei,Zhou, Hongfei,Bai, Shaokun,Li, Shaodan
supporting information, p. 3201 - 3206 (2021/03/16)
The synthesis, structure and catalytic activity of a benzene-bridged divanadium complex were comprehensively studied. The reduction of (Nacnac)VCl2(1) (Nacnac = (2,6-iPr2C6H3NCMe)2HC) supported by β-diketiminate with potassium graphite (KC8) by employing benzene as the solvent allows access to the benzene-bridged inverted-sandwich divanadium complex (μ-η6:η6-C6H6)[V(Nacnac)]2(2a), which can catalyze alkene alkylarylation with hypervalent iodine(iii) reagents (HIRs)viadecarboxylation to generate regioselectively diverse indolinones. Furthermore, the mild nature of this reaction was amenable to a wide range of functionalities on alkenes and HIRs. Mechanistic studies revealed a relay sequence of decarboxylative radical alkylation/radical arylation/oxidative re-aromatization.
Acridine Orange Hemi(Zinc Chloride) Salt as a Lewis Acid-Photoredox Hybrid Catalyst for the Generation of α-Carbonyl Radicals
Das, Sanju,De Sarkar, Suman,Mandal, Tanumoy
supporting information, (2021/12/10)
A readily accessible organic-inorganic hybrid catalyst is reported for the reductive fragmentation of α-halocarbonyl compounds. The robust hybrid catalyst is a self-stabilizing combination of ZnCl2 Lewis acid and acridine orange as the photoactive organic dye. Mechanistic specifics of this hybrid catalyst have been studied in detail using both photophysical and electrochemical experiments. A systematic study enabled the discovery of the appropriate Lewis acid for the effective LUMO stabilization of α-halocarbonyl compounds and thereby lowering of reduction potential within the range of a standard organic dye. This strategy resolves the issues like dehalogenative hydrogenation or homo-coupling of alkyl radicals by guiding the photoredox cycle through an oxidative quenching pathway. The cooperativity between the photoactive organic dye and the Lewis acid counterparts empowers functionalization with a wide range of coupling partners through efficient and controlled generation of alkyl radicals and serves as an appropriate alternative to the expensive late transition metal-based photocatalysts. To demonstrate the application potential of this cooperative catalytic system, four different synthetic transformations of α-carbonyl bromides were explored with broad substrate scopes.
The Allylic Acetoxylation of 1,1-Disubstituted Alkenes Catalyzed by a Palladium(II)/Monothiadiazole Ligand System
Jin, Can,Li, Xiaohan,Sun, Bin,Wang, Jiayang,Yang, Jin,Yu, Chuangming,Zhang, Xun,Zhuang, Xiaohui
supporting information, p. 1479 - 1483 (2019/07/15)
A palladium(II)/monothiadiazole ligand catalytic system and its application in catalyzing the acetoxylation of 1,1-disubstituted alkenes have been developed. With this newly designed monothiadiazole thioether ligand, the reaction showed a broad scope with respect to 1,1-disubstituted olefins, giving the corresponding products in yields of 30-86percent.
Regioselective Acetoxylation of Terminal Olefins Using a Palladium(II)–Thiadiazole Catalyst
Li, Xiaohan,Sun, Bin,Zhou, Jiadi,Jin, Can,Yu, Chuangming
supporting information, p. 2635 - 2638 (2019/04/04)
First-time use of a palladium(II)–thiadiazole catalyst in the allylic oxidation of terminal olefins to linear allylic acetates. Employing this strategy, a range of allylic esters (20 examples) were synthesized in 43 % to 80 % yield with excellent regio- and stereoselectivities.
Catalyst-free and selective trifluoromethylative cyclization of acryloanilides using PhICF3Cl
Guo, Jia,Xu, Cong,Wang, Ling,Huang, Wanqiao,Wang, Mang
supporting information, p. 4593 - 4599 (2019/05/17)
Trifluoromethylation-triggered cyclization of alkenes provides a useful route to CF3-containing cyclic compounds. Current approaches to generate CF3-based initiators from a CF3 source require a catalyst or an activator. This work describes a catalyst-free protocol to innately produce electrophilic CF3 species from PhICF3Cl for trifluoromethylative cyclization of acryloanilides. A new domino biscyclization of dienes has been developed leading to trifluoroethylated tetrahydroindenoquinolinones with chemo- and stereo-selectivity.
Dehydrogenative Silylation of Alkenes for the Synthesis of Substituted Allylsilanes by Photoredox, Hydrogen-Atom Transfer, and Cobalt Catalysis
Yu, Wan-Lei,Luo, Yong-Chun,Yan, Lei,Liu, Dan,Wang, Zhu-Yin,Xu, Peng-Fei
supporting information, p. 10941 - 10945 (2019/07/17)
A synergistic catalytic method combining photoredox catalysis, hydrogen-atom transfer, and proton-reduction catalysis for the dehydrogenative silylation of alkenes was developed. With this approach, a highly concise route to substituted allylsilanes has been achieved under very mild reaction conditions without using oxidants. This transformation features good to excellent yields, operational simplicity, and high atom economy. Based on control experiments, a possible reaction mechanism is proposed.
Nickel-Catalyzed Transformation of Diazoacetates to Alkyl Radicals Using Alcohol as a Hydrogen Source
Zhao, Jingjing,Li, Pan,Xu, Yaohua,Shi, Yixin,Li, Fuwei
supporting information, p. 9386 - 9390 (2019/11/28)
A nickel-catalyzed transformation of diazoacetates to α-carbonyl methylene radicals has been disclosed in the presence of hyperoxide using ethanol as a hydrogen source and solvent. This strategy is successfully applied in the formation of indolin-2-ones or 1,4-dicarbonyl compounds from acrylamides or enamides in moderate to good yields. These reactions undergo radical addition onto C-C double bonds followed by a cyclization/oxidation or an oxidation/hydrolysis process, respectively.
Synthesis of oxindoles via Cu-mediated reactions between N-phenylacrylamides and ethyl 2-bromo-2-methylpropionate
Liu, Da,Zhuang, Shaobo,Chen, Xiang,Yu, Lin,Yu, Yongqi,Hu, Liang,Tan, Ze
supporting information, p. 612 - 616 (2018/01/18)
A novel way of synthesizing alkylated oxindoles via Cu-mediated atom transfer radical addition reaction between N-phenylacrylamides and ethyl 2-bromo-2-methylpropionate has been described. It was found that the use of N,N,N′,N′-1,1,2,2,-tetramethylethylenediamine as ligand was important for achieving good yields. Additionally, the use of DMSO as solvent and running the reaction at 130 °C were also crucial. In some cases, the product can be further brominated when the reaction temperature was raised to 150 °C.
Iron-Catalyzed Synthesis of Oxindoles: Application to the Preparation of Pyrroloindolines
Correia, Valquírio G.,Abreu, Juliana C.,Barata, Caio A. E.,Andrade, Leandro H.
supporting information, p. 1060 - 1063 (2017/03/15)
A novel and highly efficient synthetic approach to pyrroloindolines has been developed. The process is based on tandem radical addition/cyclization with inexpensive iron catalyst. This method tolerates a wide range of N-methyl-N-arylacrylamides as well carbamoyl radicals, providing access to a variety of functionalized 3,3-disubstituted oxindoles, key intermediates for many bioactive pyrroloindolines such as (±)-esermethole, (±)-deoxyeseroline, and (±)-physovenol methyl ether.
