Tejas Prabakar

Shiv Nadar University

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Subhabrata Sen

Shiv Nadar University

Debajit Maiti

Shiv Nadar University

Souvik Guha

Shiv Nadar University

Ranajit Das

Shiv Nadar University

Poushaly Ghosh

Shiv Nadar University

Naiwrit Karmodak

Shiv Nadar University

S. Ankul Singh

Dr. M.G.R. Educational and Research Institute

Anubhuti Srivastava

Shiv Nadar University

Saibal Sar

Shiv Nadar University

Subhankar Bera

S.N. Bose National Centre for Basic Sciences

Cooperative Institutions

Shiv Nadar University

Institute of Child Health

Technical University of Denmark

University of North Texas

Indian Institute of Science Bangalore

Dr. M.G.R. Educational and Research Institute

SRM Institute of Science and Technology

Banner - University Medical Center Tucson

Harvard University

Harvard University Press

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Blue Light-Emitting Diode-Induced Direct C–H Functionalization of 1,4-Quinones with Aryl and Alkyl Boronic Acids

The Journal of Organic Chemistry (2022)

Souvik Guha Tejas Prabakar Subhabrata Sen

A direct functionalization of numerous 1,4-quinones with various aryl boronic acids is reported under blue light-emitting diodes (LEDs). This reaction occurs at room temperature in an open flask without any catalysts, base, and oxidants in acetonitrile (ACN) and is scalable in grams. With diverse 1,4-quinones like 1,4-benzo-, naphtho-, anthra-, and 4-bromonaphthoquinones as substrates, facile cross coupling reactions occur with aryl and alkyl boronic acids without assistance from any photocatalysts. 2-Alkylated cyclohexene-1,4-diones were obtained when the 1,4-quinones were reacted with alkyl boronic acids under standard reaction conditions. However, slight warming of the reaction mixture afforded the desired alkylated 1,4-quinones. The reaction is believed to proceed through the blue LED-induced radical formation of the aryl rings assisted by the 1,4-quinones.

Surface Modification

Boronic acid

Photoredox catalysis

10.1021/acs.joc.2c01972

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A One Pot Diazo Installation-Photochemical Oxidation (Blue Led-O2)/ Amidation of Aryl/Heteroaryl Acetates with Cyclic 2°-Amines: An Eco-Friendly Synthesis of Aromatic Α-Ketoamides

SSRN Electronic Journal (2022)

Subhabrata Sen Debajit Maiti Tejas Prabakar Poushaly Ghosh

Aromatic-α-ketoamides are an interesting class of molecules. They have myriad biological properties and are also frequently used as building blocks for the synthesis of heterocyclic scaffolds. Herein we have reported an eco-friendly synthesis of aromatic-α-ketoamides. It is a one pot synthesis beginning from alkyl aryl/heteroaryl acetates 7a - k with various cyclic secondary amines 8a - c in molecular oxygen as the oxidant via diazo installation-oxidation-amidation in ethyl acetate as solvent with blue LED (5 - 6 W Micro Photochemical Reactor (ALDKIT001)) with blue LED lights (435 - 445 nm) source) to the target compounds. The reaction could also be performed under air with no oxidant but that facilitated major formation of the undesired NH-inserted products. Under oxygen atmosphere the formation of such by-products was minimized to 10 to 20%. Various aromatic-α-ketoamides 10a - v were synthesized in moderate to good yields. Control experiments provided rational for the mechanism of transformation. This protocol could be scaled up in gram scale.

Cyclic amines

10.2139/ssrn.4127323

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Manganese‐Catalyzed CH Functionalization Reactions of Arenes

Handbook of CH‐Functionalization (2022)

Subhabrata Sen Tejas Prabakar

Abstract Manganese‐catalyzed CH functionalization reactions have evolved as an efficient strategy to construct new CC, CN, CO, and CS bonds and provide an alternative pathway to classical cross‐coupling reactions. Unlike the classical cross‐coupling catalysts like palladium (Pd) and iridium (Ir) or toxic 4d and 5d transition metal catalysts like rhenium (Re) and rhodium (Rh) that have been used for CH functionalization, 3d transition metals will be an excellent choice. Manganese is one of the most nontoxic and earth‐abundant metals available at a very low cost. Subsequently, usage of manganese catalysts has vastly increased mainly because of their application in the synthesis of active pharmaceutical ingredients. Herein, we will discuss various arene and olefin CH functionalization reactions catalyzed by manganese and assisted by diverse directing groups. The article will culminate in a discussion of the applications of manganese‐catalyzed CH functionalization via radical pathways for the generation of interesting heterocycles.

Surface Modification

10.1002/9783527834242.chf0120

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Theoretical studies to predict the utility of diazo esters in their reactions with 1,4-quinones: experimental validation via a visible light driven metal free process

Organic Chemistry Frontiers (2023)

Tejas Prabakar Subhankar Bera S. Ankul Singh Anubhuti Srivastava M. Chandrachood

Herein we report theoretical and experimental studies that revealed two different reactivity of various 1,4-quinones with electronically different diazo acetates (electron acceptor–electron donor, acceptor and acceptor–acceptor) under blue LED.

Acceptor

Electron acceptor

Reactivity

10.1039/d3qo01275a

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Citations (1)

A one pot diazo installation-photochemical oxidation (blue LED-O2)/ amidation of aryl/heteroaryl acetates with cyclic 2°-amines: An eco-friendly synthesis of aromatic α-ketoamides

Tetrahedron (2022)

Debajit Maiti Tejas Prabakar Poushaly Ghosh Subhabrata Sen

10.1016/j.tet.2022.133043

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Citations (2)

CCDC 2110512: Experimental Crystal Structure Determination

The Cambridge Structural Database (2022)

Debajit Maiti Ranajit Das Tejas Prabakar Subhabrata Sen

10.5517/ccdc.csd.cc28v51c

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Blue LED induced solvent-free multicomponent reactions among aryl diazoacetates, pyridine derivatives and maleimides: direct eco-friendly synthesis of densely functionalized itaconimides

Green Chemistry (2022)

Debajit Maiti Ranajit Das Tejas Prabakar Subhabrata Sen

We report a multicomponent reaction involving pyridine and its derivatives, aryl diazoesters and N -alkylmaleimides, using a blue LED under neat (solvent-free) conditions and in the absence of any metal catalysts or bases at r. t. to generate densely substituted itaconimides.

Environmentally Friendly

10.1039/d1gc03546k

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Citations (19)

Blue Light-Emitting Diode-Mediated In Situ Generation of Pyridinium and Isoquinolinium Ylides from Aryl Diazoesters: Their Application in the Synthesis of Diverse Dihydroindolizine

The Journal of Organic Chemistry (2021)

Saibal Sar Souvik Guha Tejas Prabakar Debajit Maiti Subhabrata Sen

Blue light-emitting diode-mediated environmentally sustainable three component reactions among pyridine/isoquinoline 1/2, aryl diazoesters 3, and acrylic ester/3-alkenyl oxindoles 5/6 provide various dihydroindolizines 7 to 9 in excellent yield. The principle of the strategy is photolytic generation of nitrogen ylides from N-heteroarenes and aryl diazoesters and their subsequent [3 + 2] cycloaddition reaction with dipolarophiles. Detailed mechanistic analysis of the transformation through control experiments establishes this strategy as the foundation for the photolytic multicomponent reaction.

Isoquinoline

10.1021/acs.joc.1c01209

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Citations (15)