1864-94-4Relevant articles and documents
Understanding the efficacy of N,N-dimethylformamide and oxalyl chloride combination as chemoselective O-formylating agent: An unified experimental and theoretical study
Batuta, Shaikh,Ali, Md. Ashif,Chatterjee, Anirban,Alam, Md. Niharul,Das, Sreeparna,Mandal, Debabrata,Begum, Naznin Ara
, p. 692 - 700 (2016)
We have developed a simple but efficient synthetic protocol for the O-formylation of a wide range of aromatic hydroxyl/phenolic substrates using an N,N-dimethylformamide (DMF) and oxalyl chloride [(COCl)2] combination in dichloromethane (DCM) as solvent at ambient temperature. The DMF/(COCl)2combination was found to be highly chemoselective for the aromatic/phenolic hydroxyl group over aliphatic hydroxyl or aromatic amine/thiol groups. This chemoselectivity of DMF/(COCl)2combination towards O-formylation of aromatic alcohols was explained on the basis of outcomes of both experimental and density functional theory–based theoretical studies.
Urchin-like Nb2O5 hollow microspheres enabling efficient and selective photocatalytic C–C bond cleavage in lignin models under ambient conditions
Chen, Huan,Hong, Donghui,Long, Donghui,Niu, Bo,Wan, Kun,Wang, Junjie,Zhang, Yayun
, (2022/03/27)
Selective cleavage of robust C?C bonds to harvest value-added aromatic oxygenates is an intriguing but challenging task in lignin depolymerization. Photocatalysis is a promising technology with the advantages of mild reaction conditions and strong sustainability. Herein, we show a novel urchin-like Nb2O5 hollow microsphere (U-Nb2O5 HM), prepared by one-pot hydrothermal method, are highly active and selective for Cα?Cβ bond cleavage of lignin β-O-4 model compounds under mild conditions, achieving 94% substrate conversion and 96% C?C bond cleavage selectivity. Systematic experimental studies and density functional theory (DFT) calculations revealed that the superior performance of U-Nb2O5 HMs arises from more exposed active sites, more efficient free charge separation and the active (001) facet, which facilitates the activation of Cβ?H bond of lignin models and generate key Cβ radical intermediates by photogenerated holes, further inducing the Cα?Cβ bond cleavage to produce aromatic oxygenates. This work could provide some suggestions for the fabrication of hierarchical photocatalysts in the lignin depolymerization system.
Oxidative α-C-C Bond Cleavage of 2° and 3° Alcohols to Aromatic Acids with O2at Room Temperature via Iron Photocatalysis
Zhang, Zongnan,Zhang, Guoxiang,Xiong, Ni,Xue, Ting,Zhang, Junjie,Bai, Lu,Guo, Qinyue,Zeng, Rong
supporting information, p. 2915 - 2920 (2021/05/05)
The selective α-C-C bond cleavage of unfunctionalized secondary (2°) and tertiary alcohols (3°) is essential for valorization of macromolecules and biopolymers. We developed a blue-light-driven iron catalysis for aerobic oxidation of 2° and 3° alcohols to acids via α-C-C bond cleavages at room temperature. The first example of oxygenation of the simple tertiary alcohols was reported. The iron catalyst and blue light play critical roles to enable the formation of highly reactive O radicals from alcohols and the consequent two α-C-C bond cleavages.
Synthesis of Indoles by Reductive Cyclization of Nitro Compounds Using Formate Esters as CO Surrogates
Ahmed Fouad, Manar,Ferretti, Francesco,Formenti, Dario,Milani, Fabio,Ragaini, Fabio
supporting information, p. 4876 - 4894 (2021/09/20)
Alkyl and aryl formate esters were evaluated as CO sources in the Pd- and Pd/Ru-catalyzed reductive cyclization of 2-nitrostyrenes to give indoles. Whereas the use of alkyl formates requires the presence of a ruthenium catalyst such as Ru3(CO)12, the reaction with phenyl formate can be performed by using a Pd/phenanthroline complex alone. Phenyl formate was found to be the most effective CO source and the desired products were obtained in excellent yields, often higher than those previously reported using pressurized CO. The reaction tolerates many functional groups, including sensitive ones like a free aldehydic group or a pendant pyrrole. Detailed experiments and kinetic studies allow to conclude that the activation of phenyl formate is base-catalyzed and that the metal doesn't play a role in the decarbonylation step. The reactions can be performed in a single thick-walled glass tube with as little as 0.2 mol-% palladium catalyst and even on a 2 g scale. The same protocol can be extended to other nitro compounds, affording different heterocycles.