Browsing by Author "Ganesh Pandey"

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Direct Arylation of Distal and Proximal C(sp3)-H Bonds of t-Amines with Aryl Diazonium Tetrafluoroborates via Photoredox Catalysis
(American Chemical Society, 2021) Pradip Kumar Mondal; Sandip Kumar Tiwari; Pushpendra Singh; Ganesh Pandey
A visible light-mediated arylation protocol for t-amines has been reported through the coupling of γ- and α-amino alkyl radicals with different aryl diazonium salts using Ru(bpy)3Cl2·6H2O as a photocatalyst. Structurally different 9-aryl-9,10-dihydroacridine, 1-aryl tetrahydroisoquinoline, hexahydropyrrolo[2,1-a]isoquinoline, and hexahydro-2H-pyrido[2,1-a]isoquinoline frameworks with different substitution patterns have been synthesized in good yield using this methodology. © 2021 American Chemical Society.
Heterocyclization involving benzylic C(sp3)-H functionalization enabled by visible light photoredox catalysis
(Royal Society of Chemistry, 2019) Ganesh Pandey; Ramkrishna Laha; Pradip Kumar Mondal
A general and efficient method for heterocyclization involving benzylic C(sp3)-H functionalization enabled by visible light photoredox catalysis to access a wide range of structurally diverse oxygen as well as nitrogen heterocycles up to a gram scale is reported. The potential application of this new methodology is demonstrated by the total synthesis of (-)-codonopsinine and (+)-centrolobine. Herein it is proposed that selectfluor, unlike a fluorinating reagent, acts as an oxidative quencher and a hydrogen radical acceptor. © The Royal Society of Chemistry 2019.
Intramolecular Cyclization of -COY (Y = OH, NHPh) to Photoredox Functionalized Benzylic C(sp3)-H Bond. Attractive Approach to Construct γ, δ-lactones and lactams Scaffolds
(John Wiley and Sons Inc, 2024) Kumari Swati Sharma; Sandip Kumar Tiwari; Ganesh Pandey
Synthesis of γ and δ-lactones and lactams are reported in high yield by the cyclization of −COY (Y=OH, NHPh) to the photo redox functionalized benzylic C(sp3)−H bond. © 2024 Wiley-VCH GmbH.
P-Silylation of Arenes via Organic Photoredox Catalysis: Use of p-Silylated Arenes for Exclusive o-Silylation, o-Acylation, and o-Alkylation Reactions
(American Chemical Society, 2021) Ganesh Pandey; Sandip Kumar Tiwari; Pushpendra Singh; Pradip Kumar Mondal
Photocatalytic regiospecific p-silylation of arenes has been achieved by the coupling of in situ generated silyl radical with arene radical cation. The strategy involves reductive activation of PhSe-SiR3 and single electron transfer from the electron rich arene to 9,10-dimethoxyanthracene radical cation (DMA•+). p-Silyl arenes, thus formed, are further utilized for exclusive o-silylation reaction and for regiospecific o-acylation as well as o-alkylation reaction. © 2021 American Chemical Society.
Regioselective C(sp2)-H imidation of arenes by redox neutral visible-light photocatalysis
(Royal Society of Chemistry, 2022) Manoj Kumar Ghosh; Kumari Swati Sharma; Ganesh Pandey
We report herein a redox neutral visible light-induced regioselective C(sp2)-H imidation of electron-rich arenes and heteroarenes using conceptually designed redox-active 1 as a source of the N-centered imidyl radical. Structurally diverse aromatic imides were obtained in moderate to good yields. This methodology has been successfully employed for the late stage imidation of complex molecules and has also been applied towards the formal total synthesis of the marine natural products carpatamides A, B and D. It has further been shown that the generated imides can easily be converted to the corresponding anilines in situ directly. © 2023 The Royal Society of Chemistry.
Synthesis of 2-Azabicyclo[m.n.0]–Alkanes and Their Application towards the Synthesis of Strychnos and Stemona Classes of Alkaloids
(Wiley-VCH Verlag, 2020) Binoy Majumder; Ganesh Pandey
2-Azabicyclo[m.n.0]alkane ring systems, the conceptual precursors towards the synthesis of Strychnos and Stemona classes of alkaloids, were synthesized from tert-butyl 2-(phenylsulfonyl)-7-aza-bicyclo[2.2.1]hept-2-ene-7-carboxylate by alkyl Grignard reaction and intramolecular cyclisation of the in situ generated ring opening product 2. The synthesized cis-hexahydroindole 3 and cis-octahydro-benzo[b]azepine 5 scaffolds were utilized to construct the advanced intermediates 25 and 35, respectively, towards the synthesis of the corresponding Strychnos and Stemona classes of alkaloids. © 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Visible-Light-Induced Secondary Benzylic C(sp3)-H Functionalization for Nucleophilic Substitution: An Intermolecular C-X (C-N, C-C, and C-Br) Bond Forming Reaction
(American Chemical Society, 2025) Kumari Swati Sharma; Nagender Thadem; Ganesh Pandey
Exploring new synthetic methods that harness visible light represents a breakthrough in organic synthesis. Amides, amines, nitriles, and halides are essential functional groups and serve as key building blocks in the synthesis of complex molecules in organic and medicinal chemistry. This study introduces a novel intermolecular benzylic C-X (C-N, C-C, and C-Br) bond formation via photoredox benzylic C(sp3)-H bonds. This methodology enables the synthesis of secondary amides, nitriles, and halides through reacting secondary benzylic substrates with readily accessible reagents including BocNH2, benzamide, acetamide, TMSCN, and TBAB. This approach displays the potential of being sustainable and efficient to afford amidation, cyanation, and halogenation products in good yields. © 2025 American Chemical Society.