LMCT-Driven Iron Photocatalysis: Mechanistic Insights and Synthetic Applications Amrita Chaudhuri, Luca Mareen Denkler, Qing Zhuo, Anup Mandal, Ala Bunescu Chemistry A European Journal, 2025 Iron‐based photocatalysis has emerged as a sustainable and versatile platform for facilitating a wide range of chemical transformations, offering an appealing alternative to precious metal photocatalysts. Among the various activation modes, ligand‐to‐metal charge transfer (LMCT)‐driven homolysis of Fe(III)–L(ligand) bonds has garnered considerable attention due to its ability to generate reactive radical species under mild conditions, without requiring the matching of substrates’ redox potentials. In this review, we present a comprehensive overview of recent developments in LMCT‐driven iron photocatalysis, with a particular focus on both mechanistic insights and synthetic applications published in the last five years. We classify Fe(III)–L homolysis into four major categories based on the nature of the coordinated ligand: halides, carboxylates, alkoxides, and azide. For a few cases, mechanistic understanding derived from spectroscopic studies, computational modeling, and kinetic investigations is discussed in more detail. We further highlight the expanding repertoire of synthetic transformations enabled by LMCT‐driven iron photocatalysis, including C─H functionalization, alkene functionalization, cross‐coupling, oxidation, and radical‐mediated bond formation. Finally, we provide future perspectives on the continued development of LMCT‐based iron photocatalysis as a broadly applicable platform for sustainable organic synthesis. This review aims to serve as a valuable resource for researchers interested in leveraging the full potential of LMCT‐mediated iron photocatalysis in modern organic chemistry.
Extensive Studies on the Synthesis and Characterization of π-Arene Chromium Complexes and Their Performance in SNAr and Suzuki–Miyaura Cross-Coupling Reactions Clemens Maurer, Ruben Fleischer, Anup Mandal, Kavin Raj Kumar Chandramohan, Fabian Christophe Herpell, Christopher Heinz Köhler, Defne Cetin, Gregor Schnakenburg, Ala Bunescu Chemistry an Asian Journal, 2025 We report an efficient synthesis of a series of new (η6‐arene)Cr(CO)3 complexes via ligand exchange strategy under thermal conditions using chromium hexacarbonyl and readily accessible arene feedstocks. We optimized the previously reported procedures and found that the high excess of arenes usually employed is not required to access the π‐arene chromium complexes in high yields. Consequently, the revised procedure simplifies the purification of chromium tricarbonyl complexes bearing arenes with high boiling points. The reaction is amenable to provide (η6‐arene)Cr(CO)3 complexes decorated with various functional groups. Notably, the novel and already reported chromium complexes with missing spectroscopic characterization were fully characterized by nuclear magnetic resonance (NMR), infrared (IR) spectroscopies, and high‐resolution mass spectrometry (HRMS). Besides, we report the structure of 20 chromium complexes characterized via X‐ray crystallography. The potential application of these π‐arene chromium complexes has also been exploited toward the selective construction of poly(hetero)aryls possessing a single chromium tricarbonyl unit through SNAr and Suzuki–Miyaura cross‐coupling reactions. This work is meant to be a practical guide for the synthesis of π‐arene chromium complexes and to fill the gap in their spectroscopic characterization.
Selective C-H Borylation of Polyaromatic Compounds Enabled by Metal-Arene π-Complexation Anup Mandal, Clemens Maurer, Christoph Plett, Kavin Raj Kumar Chandramohan, Ruben Fleischer, Gregor Schnakenburg, Stefan Grimme, Ala Bunescu Journal of the American Chemical Society, 2025 The undirected Ir-catalyzed C-H borylation usually occurs preferentially at the least hindered and more acidic C-H bond of the aromatic ring. In the case of polyaromatic compounds possessing multiple unbiased and sterically accessible C-H bonds, the site selectivity for the nondirected C-H borylation is low. Here, we report the dramatic effect exerted by the π-complexation of a chromium tricarbonyl unit on the aromatic ring in the context of Ir-catalyzed C-H borylation. Competition experiments demonstrate that the C-H bonds of an aromatic ring bound to the chromium tricarbonyl unit react on average two orders in magnitude faster toward the C-H borylation than the unbound arenes. This enables an unprecedented C-H borylation with high site selectivity of the aromatic ring π-complexed with a chromium tripod in a series of organic polyaromatic compounds. Besides, the drastic enhancement of the reactivity of C-H bonds induced by the chromium tripod allows the C-H borylation to occur at room temperature with the substrate as a limiting reagent. The DFT studies indicate that the oxidative addition of the C-H bonds has lower activation barriers when the arenes are complexed with a chromium tricarbonyl unit, explaining the observed exceptional site selectivity. This study will further spearhead the development of nondirected C-H borylation with a bimetallic system to harness the effect of the noncovalent metal-arene π-type interactions on the reactivity and the selectivity of the C-H functionalization.
Palladium-Catalyzed Electrooxidative Hydrofluorination of Aryl-Substituted Alkenes with a Nucleophilic Fluorine Source Anup Mandal, Jieun Jang, Baeho Yang, Hyunwoo Kim, Kwangmin Shin Organic Letters, 2023 Herein, we report an electrocatalytic hydrofluorination of aryl-substituted alkenes with a nucleophilic fluorine source. The merger of palladium catalysis with electrooxidation enables the transformation of various substrates ranging from styrenes to more challenging α,β-unsaturated carbonyl derivatives to the corresponding benzylic fluorides. This method can also be applied to the late-stage modification of pharmaceutical derivatives. Mechanistic studies suggest that the generation of a high-valent palladium intermediate via anodic oxidation is the crucial step in this electrocatalytic hydrofluorination.
Regioselective C-H Alkenylation and Unsymmetrical Bis-olefination of Heteroarene Carboxylic Acids with Ruthenium Catalysis in Water Anup Mandal, Ratnadeep Bera, Mahiuddin Baidya Journal of Organic Chemistry, 2021 An efficient weak carboxylate-assisted oxidative cross-dehydrogenative C–H/C–H coupling (CDC) of heteroarenes with readily available olefins has been devised employing water as green solvent under ruthenium(II) catalysis. The reaction is operationally simple, accommodates a large variety of heteroaromatic carboxylic acids as well as olefins, and facilitates a diverse array of high-value olefin-tethered heteroarenes in high yields (up to 87%). The potential of this ortho-C–H bond activation strategy has also been exploited toward tunable synthesis of densely functionalized heteroarenes through challenging unsymmetrical bis-olefination process in a one-pot sequential fashion. Mechanistic investigation demonstrates a reversible ruthenation process and C–H metalation step might not be involved in the rate-determining step.
Cross-Dehydrogenative Coupling/Annulation of Arene Carboxylic Acids and Alkenes in Water with Ruthenium(II) Catalyst and Air Anup Mandal, Bholanath Garai, Suman Dana, Ratnadeep Bera, Mahiuddin Baidya Chemistry an Asian Journal, 2020 A cross‐dehydrogenative coupling of arene carboxylic acids with olefins is reported with ruthenium(II) catalyst employing air and water as green oxidant and solvent, respectively. It offers a robust synthesis of valuable phthalide molecules. A one‐pot sequential strategy is also disclosed to access Heck‐type products that are apparently difficult to make directly from arene carboxylic acids.
Copper-Catalyzed 8-Aminoquinoline-Directed Oxidative C-H/N-H Coupling for N-Arylation of Sulfoximines Gowri Sankar Grandhi, Suman Dana, Anup Mandal, Mahiuddin Baidya Organic Letters, 2020 A copper-catalyzed cross-dehydrogenative C–H/N–H coupling has been devised to access a series of N-arylated sulfoximines in high yield from 8-aminoquinoline-derived benzamides and sulfoximines. The reaction is scalable, and mechanistic studies favor the involvement of an organometallic pathway, where C–H bond cleavage is presumed to be the kinetically relevant step. The utility of sulfoximine-coupled benzamides was displayed through the nickel-catalyzed acceptorless dehydrogenative olefination of benzyl alcohols.
Atom Transfer Oxidative Radical Cascade of Aryl Alkynoates towards 1,1-Dichalcogenide Olefins Harekrishna Sahoo, Isai Ramakrishna, Anup Mandal, Mahiuddin Baidya Chemistry an Asian Journal, 2019 An oxidative trifunctionalization of aryl alkynoates has been devised via the chalcogenide radical triggered intramolecular 1,4‐aryl migration/decarboxylation cascade to prepare 1,1‐dichalcogenide tetrasubstituted alkenes in high yields (up to 98 %). This operationally simple reaction proceeds under metal‐free conditions, can be executed on gram scale, and highlights formal 1,1‐difunctionalization of alkynes. Synthetic potential of this protocol was demonstrated through a twofold cascade rearrangement to access highly conjugated tetra‐selenylated alkenes along with a cross‐dehydrogenative annulation to prepare fluorene derivative.
Recent Advancements in Transition-Metal-Catalyzed One-Pot Twofold Unsymmetrical Difunctionalization of Arenes Anup Mandal, Suman Dana, Deepan Chowdhury, Mahiuddin Baidya Chemistry an Asian Journal, 2019 Transition‐metal‐catalyzed direct C−H bond activation reactions have been embraced as a powerful synthetic tool to access diverse functionalized arenes. However, site‐selective incorporation of multiple distinct functionalities in an arene has always been a formidable challenge. Recent efforts from the synthetic community have disclosed a few dynamic synthetic approaches to fabricate multifunctionalized arenes in one‐pot using a single catalytic system. These reports manifested the immense potential of such approaches to expedite contemporary organic synthesis towards building molecular complexity. In this minireview, we have illustrated the recent progress in this area, highlighting the contribution from several synthetic chemists including our group.
Streamlined Ruthenium(II) Catalysis for One-Pot 2-fold Unsymmetrical C-H Olefination of (Hetero)Arenes Anup Mandal, Gunjan Mehta, Suman Dana, Mahiuddin Baidya Organic Letters, 2019 The potential of carboxylate-directed Ru(II)-catalyzed C–H bond activation has been exploited in the first example of challenging 2-fold unsymmetrical cross-dehydrogenative olefination of (hetero)aromatic carboxylic acids. This highly regioselective protocol operates in one pot under a single catalytic system and tolerates a wide spectrum of carboxylic acids as well as activated olefins. A rare example of an unsymmetrical meta-bis-olefination approach has also been successfully engineered via a tailored unsymmetrical double C–H functionalization and concomitant decarboxylation process.
Cobalt-Catalyzed Site Selective C–H Borylation of Polyarenes via π-Activation Strategy X Zhu‡, A Mandal‡, M Zafar, C Maurer, G Schnakenburg, A Bunescu* ChemRxiv Preprint, DOI: 10.26434/chemrxiv.15001073/v1 , 2026 2026
Conformation-Guided Meta-Selective C–H Borylation via Metal-Arene π-Complexation A Mandal‡, C Maurer‡, M Zafar, A Chaudhuri, X Zhu, ... ChemRxiv Preprint, doi.org/10.26434/chemrxiv.15000133/v1 , 2026 2026
LMCT-Driven Iron Photocatalysis: Mechanistic Insights and Synthetic Applications A Chaudhuri*‡, LM Denkler‡, Q Zhuo‡, A Mandal*‡, A Bunescu* Chemistry - A European Journal, 31, e02185 , 2025 2025 Citations: 25
Selective C–H Borylation of Polyaromatic Compounds Enabled by Metal-Arene π-Complexation A Mandal‡, C Maurer‡, C Plett, KRK Chandramohan, R Fleischer, ... Journal of the American Chemical Society, 147, 15281–15293 , 2025 2025 Citations: 8
Extensive Studies on the Synthesis and Characterization of π-Arene Chromium Complexes and Their Performance in SNAr and Suzuki-Miyaura Cross-Coupling Reactions C Maurer‡, R Fleischer‡, A Mandal*‡, KRK Chandramohan, FC Herpell, ... Chemistry – An Asian Journal, 20, e202500139 , 2025 2025 Citations: 2
Palladium-Catalyzed Electrooxidative Hydrofluorination of Aryl-Substituted Alkenes with a Nucleophilic Fluorine Source A Mandal, J Jang, B Yang, H Kim*, K Shin* Organic Letters, 25, 195–199 , 2023 2023 Citations: 21
Regioselective C−H Alkenylation and Unsymmetrical Bis-olefination of Heteroarene Carboxylic Acids with Ruthenium Catalysis in Water A Mandal, R Bera, M Baidya* The Journal of Organic Chemistry, 86, 62−73 , 2021 2021 Citations: 31
Copper-Catalyzed 8‑Aminoquinoline-Directed Oxidative C–H/N–H Coupling for N‑Arylation of Sulfoximines GS Grandhi, S Dana, A Mandal, M Baidya* Organic Letters, 22, 2606−2610 , 2020 2020 Citations: 45
Cross-Dehydrogenative Coupling/Annulation of Arene Carboxylic Acids and Alkenes in Water with Ruthenium(II) Catalyst and Air A Mandal, B Garai, S Dana, R Bera, M Baidya* Chemistry – An Asian Journal, 15, 4009−4013 , 2020 2020 Citations: 20
A Ruthenium-Catalyzed Free Amine Directed (5+1) Annulation of Anilines with Olefins: Diverse Synthesis of Phenanthridine Derivatives D Chowdhury, S Dana, A Mandal, M Baidya* Chemical Communications, 55, 11908–11911 , 2019 2019 Citations: 42
Recent Advancements in Transition-Metal-Catalyzed One-Pot Twofold Unsymmetrical Difunctionalization of Arenes A Mandal‡, S Dana‡, D Chowdhury‡, M Baidya* Chemistry – An Asian Journal, 14, 4074–4086 , 2019 2019 Citations: 43
Streamlined Ruthenium(II) Catalysis for One-Pot 2‑fold Unsymmetrical C–H Olefination of (Hetero)Arenes A Mandal, G Mehta, S Dana, M Baidya* Organic Letters, 21, 5879−5883 , 2019 2019 Citations: 29
Atom Transfer Oxidative Radical Cascade of Aryl Alkynoates towards 1,1-Dichalcogenide Olefins H Sahoo, I Ramakrishna, A Mandal, M Baidya* Chemistry – An Asian Journal, 14, 4549–4552 , 2019 2019 Citations: 15
Ruthenium(II) Catalysis/Noncovalent Interaction Synergy for Cross-Dehydrogenative Coupling of Arene Carboxylic Acids S Dana, D Chowdhury, A Mandal, FAS Chipem, M Baidya* ACS Catalysis, 8, 10173−10179 , 2018 2018 Citations: 64
Ru(II)-Catalyzed Annulative Coupling of Benzoic Acids with Vinyl Sulfone via Weak Carboxylate-Assisted C–H Bond Activation A Mandal, S Dana, D Chowdhury, M Baidya* Asian Journal Of Organic Chemistry, 7, 1302–1306 , 2018 2018 Citations: 21
A Cross-Dehydrogenative Annulation Strategy towards Synthesis of Polyfluorinated Phenanthridinones with Copper A Mandal, J Selvakumar, S Dana, U Mukherjee, M Baidya* Chemistry – A European Journal, 24, 3448–3454 , 2018 2018 Citations: 20
Visible Light-Induced Synthetic Approach for Selenylative Spirocyclization of N-Aryl Alkynamides with Molecular Oxygen as Oxidant H Sahoo, A Mandal, S Dana, M Baidya* Advanced Synthesis & Catalysis, 360, 1099–1103 , 2018 2018 Citations: 106
Ru(II)-Catalyzed Oxidative Heck-Type Olefination of Aromatic Carboxylic Acids with Styrenes through Carboxylate-Assisted C–H Bond Activation S Dana, A Mandal, H Sahoo, S Mallik, GS Grandhi, M Baidya* Organic Letters, 20, 716−719 , 2018 2018 Citations: 36
Study of Antioxidant Property of the Rhizome Extract of Polygonatum cirrhifolium (Mahameda) and its use in the green synthesis of Gold nanoparticles SS Dash, A Mandal, BG Bag* Prayogik Rasayan, 1, 66-70 , 2017 2017 Citations: 1
Ruthenium(II)-Catalyzed Hydroarylation of Maleimides Using Carboxylic Acids as a Traceless Directing Group A Mandal, H Sahoo, S Dana, M Baidya* Organic Letters, 19, 4138−4141 , 2017 2017 Citations: 113
MOST CITED SCHOLAR PUBLICATIONS
Copper-Catalyzed 8-Aminoquinoline-Directed Selenylation of Arene and Heteroarene C–H Bonds A Mandal, H Sahoo, M Baidya* Organic Letters, 18, 3202−3205 , 2016 2016 Citations: 122
Ruthenium(II)-Catalyzed Hydroarylation of Maleimides Using Carboxylic Acids as a Traceless Directing Group A Mandal, H Sahoo, S Dana, M Baidya* Organic Letters, 19, 4138−4141 , 2017 2017 Citations: 113
Ruthenium(II)-Catalyzed ortho-C–H Chalcogenation of Benzoic Acids via Weak O‑Coordination: Synthesis of Chalcogenoxanthones A Mandal, S Dana, H Sahoo, GS Grandhi, M Baidya* Organic Letters, 19, 2430−2433 , 2017 2017 Citations: 113
Visible Light-Induced Synthetic Approach for Selenylative Spirocyclization of N-Aryl Alkynamides with Molecular Oxygen as Oxidant H Sahoo, A Mandal, S Dana, M Baidya* Advanced Synthesis & Catalysis, 360, 1099–1103 , 2018 2018 Citations: 106
Ruthenium(II) Catalysis/Noncovalent Interaction Synergy for Cross-Dehydrogenative Coupling of Arene Carboxylic Acids S Dana, D Chowdhury, A Mandal, FAS Chipem, M Baidya* ACS Catalysis, 8, 10173−10179 , 2018 2018 Citations: 64
Ru(II)-Catalyzed C–H Functionalization on Maleimides with Electrophiles: A Demonstration of Umpolung Strategy S Dana, A Mandal, H Sahoo, M Baidya* Organic Letters, 19, 1902−1905 , 2017 2017 Citations: 54
Copper-Catalyzed 8‑Aminoquinoline-Directed Oxidative C–H/N–H Coupling for N‑Arylation of Sulfoximines GS Grandhi, S Dana, A Mandal, M Baidya* Organic Letters, 22, 2606−2610 , 2020 2020 Citations: 45
Recent Advancements in Transition-Metal-Catalyzed One-Pot Twofold Unsymmetrical Difunctionalization of Arenes A Mandal‡, S Dana‡, D Chowdhury‡, M Baidya* Chemistry – An Asian Journal, 14, 4074–4086 , 2019 2019 Citations: 43
Remote C–H Selenylation of 8‐Amidoquinolines via Copper‐Catalyzed Radical Cross‐Coupling H Sahoo, A Mandal, J Selvakumar, M Baidya* European Journal of Organic Chemistry, 2016, 4321−4327 , 2016 2016 Citations: 43
A Ruthenium-Catalyzed Free Amine Directed (5+1) Annulation of Anilines with Olefins: Diverse Synthesis of Phenanthridine Derivatives D Chowdhury, S Dana, A Mandal, M Baidya* Chemical Communications, 55, 11908–11911 , 2019 2019 Citations: 42
Ru(II)-Catalyzed Oxidative Heck-Type Olefination of Aromatic Carboxylic Acids with Styrenes through Carboxylate-Assisted C–H Bond Activation S Dana, A Mandal, H Sahoo, S Mallik, GS Grandhi, M Baidya* Organic Letters, 20, 716−719 , 2018 2018 Citations: 36
Regioselective C−H Alkenylation and Unsymmetrical Bis-olefination of Heteroarene Carboxylic Acids with Ruthenium Catalysis in Water A Mandal, R Bera, M Baidya* The Journal of Organic Chemistry, 86, 62−73 , 2021 2021 Citations: 31
Streamlined Ruthenium(II) Catalysis for One-Pot 2‑fold Unsymmetrical C–H Olefination of (Hetero)Arenes A Mandal, G Mehta, S Dana, M Baidya* Organic Letters, 21, 5879−5883 , 2019 2019 Citations: 29
LMCT-Driven Iron Photocatalysis: Mechanistic Insights and Synthetic Applications A Chaudhuri*‡, LM Denkler‡, Q Zhuo‡, A Mandal*‡, A Bunescu* Chemistry - A European Journal, 31, e02185 , 2025 2025 Citations: 25
Palladium-Catalyzed Electrooxidative Hydrofluorination of Aryl-Substituted Alkenes with a Nucleophilic Fluorine Source A Mandal, J Jang, B Yang, H Kim*, K Shin* Organic Letters, 25, 195–199 , 2023 2023 Citations: 21
Ru(II)-Catalyzed Annulative Coupling of Benzoic Acids with Vinyl Sulfone via Weak Carboxylate-Assisted C–H Bond Activation A Mandal, S Dana, D Chowdhury, M Baidya* Asian Journal Of Organic Chemistry, 7, 1302–1306 , 2018 2018 Citations: 21
Cross-Dehydrogenative Coupling/Annulation of Arene Carboxylic Acids and Alkenes in Water with Ruthenium(II) Catalyst and Air A Mandal, B Garai, S Dana, R Bera, M Baidya* Chemistry – An Asian Journal, 15, 4009−4013 , 2020 2020 Citations: 20
A Cross-Dehydrogenative Annulation Strategy towards Synthesis of Polyfluorinated Phenanthridinones with Copper A Mandal, J Selvakumar, S Dana, U Mukherjee, M Baidya* Chemistry – A European Journal, 24, 3448–3454 , 2018 2018 Citations: 20
Atom Transfer Oxidative Radical Cascade of Aryl Alkynoates towards 1,1-Dichalcogenide Olefins H Sahoo, I Ramakrishna, A Mandal, M Baidya* Chemistry – An Asian Journal, 14, 4549–4552 , 2019 2019 Citations: 15
Selective C–H Borylation of Polyaromatic Compounds Enabled by Metal-Arene π-Complexation A Mandal‡, C Maurer‡, C Plett, KRK Chandramohan, R Fleischer, ... Journal of the American Chemical Society, 147, 15281–15293 , 2025 2025 Citations: 8