Browsing by Author "Ramesh Kumar Vishwakarma"
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PublicationArticle An Efficient Synthesis of 1,2-Diketones by Oxidative Cross-coupling of Alkynes and Aryl Triazenes using Copper Catalysis(Wiley-Blackwell, 2019) Ramesh Kumar Vishwakarma; Saurabh Kumar; Anup Kumar Sharma; Rahul Singh; Krishna Nand SinghAn efficient and mild approach to 1,2-diketones has been developed via oxidative cross-coupling of alkynes and aryl triazenes using copper catalysis under open atmosphere. The approach is convenient, clean, and offers a wide range of substrate scope and functional group tolerance. © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, WeinheimPublicationArticle Direct C-H Arylation of N-Heterocycles with Aryl Triazenes Using Molecular Oxygen as Oxidant(Wiley-Blackwell, 2019) Narendra R. Chaubey; Ramesh Kumar Vishwakarma; Krishna Nand SinghAn efficient C−H arylation of N-heterocycles has been developed using stable and easily accessible aryl triazenes in the presence of oxygen under metal- and peroxide-free conditions. The methodology is regiospecific and applicable to a wide range of electron-deficient N-heterocycles and aryl triazenes as demonstrated by 20 examples with yields ranging from 32–83%. © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, WeinheimPublicationArticle Synthesis of functionalized alkenes via Cu(i)-catalysed allylation of acetanilides using Morita-Baylis-Hillman bromides(Royal Society of Chemistry, 2023) Ramesh Kumar Vishwakarma; Krishna Nand SinghAn easy access to functionalized alkenes has been developed by the C-H functionalization of anilides with Morita-Baylis-Hillman (MBH) bromides in the presence of copper chloride, TBHP and acetic acid. Unsubstituted as well as ortho/meta-substituted anilides exclusively give rise to the para-allylated products, whereas para-substitution brings about the formation of ortho-allylated anilides. © 2023 The Royal Society of Chemistry.PublicationArticle Transition-Metal-Free Cross-Dehydrogenative Coupling of Ethyl Arylacetates with Benzoic/Cinnamic Acids: A Practical Synthesis of α-Acyloxy Esters(Wiley-VCH Verlag, 2018) Anup Kumar Sharma; Promod Kumar; Ramesh Kumar Vishwakarma; Krishna Nand SinghAn efficient cross-dehydrogenative coupling of benzylic C(sp3)−H of ethyl arylacetates with benzoic/cinnamic acids has been developed to afford α-acyloxy esters in reasonably high yields under environmentally benign conditions. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, WeinheimPublicationArticle Visible-Light-Enabled Synthesis of Pyridyl Benzamides via Oxidative Decarbethoxylation using Copper(I) Iodide/Air at Room Temperature(Wiley-VCH Verlag, 2019) Anup Kumar Sharma; Promod Kumar; Ramesh Kumar Vishwakarma; Krishna Nand SinghAn efficient synthesis of N-(pyridin-2-yl)benzamides has been developed by the reaction of 2-aminopyridines and ethyl arylacetates via oxidative decarbethoxylation using visible light/CuI/O2 in acetonitrile at room temperature. © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, WeinheimPublicationArticle Visible-Light-Induced Photocatalytic Synthesis of β-Keto Dithiocarbamates via Difunctionalization of Styrenes(American Chemical Society, 2021) Ramesh Kumar Vishwakarma; Saurabh Kumar; Krishna Nand SinghA facile photocatalyzed strategy for difunctionalization of styrenes in the presence of CS2 and amines providing β-keto dithiocarbamates has been developed. In the case of 4-nitrostyrene and 2-vinylpyridine, however, only 2-arylethylthiocarbamates are interestingly formed without the aid of photoredox catalysis/TBHP. © 2021 American Chemical Society. All rights reserved.PublicationArticle Visible-light-mediated C(sp3)-H functionalization of alkyl arylacetates: an easy approach to S-benzyl dithiocarbamate acetates(Royal Society of Chemistry, 2022) Mahesh Kumar; Ramesh Kumar Vishwakarma; Preeti; Krishna Nand SinghAn efficient visible light-promoted C(sp3)-H functionalization of alkyl arylacetates has been developed using CS2 and amines by eosin Y/I2 dual catalysis to achieve the formation of S-benzyl dithiocarbamate acetates. © 2023 The Royal Society of Chemistry.