Lisa Roy

Indian Institute of Technology Kharagpur | IIT KGP · Department of Education

We report a sustainable and eco-friendly approach for selective N-alkylation of various amines by alcohols, catalyzed by a well-defined Zn(II)-catalyst, Zn(La)Cl2 (1a), bearing a tridentate arylazo scaffold. A total of 57 N-alkylated amines were prepared in good to excellent yields, out of which 17 examples are new. The Zn(II)-catalyst shows wide f...

We conceptualized a novel disconnection approach for the synthesis of fused tetrahydroquinolines that exploits a visible light-mediated radical (4 + 2) annulation between alkyl N-(acyloxy)phthalimides and N-substituted maleimides in the presence of DIPEA as an additive. The reaction proceeds through the formation of a photoactivated electron donor-...

An electrochemical method for the synthesis of unsymmetrically substituted NH‐pyrroles is described. The synthetic strategy comprises a challenging heterocoupling between two structurally diverse enamines via sequential chemoselective oxidation, addition, and cyclization processes. A series of aryl‐ and alkyl‐substituted enamines were effectively c...

This article reports π-chromophore assemblies from three structurally related dipolar naphthalene monoimide (NMI) luminogens (M1, M2 and M3) by underexplored orthogonal dipole-dipole interaction and halogen bonding. Single crystal structure analysis...

An acceptorless dehydrogenative strategy for the synthesis of polyfluoroalkylated bis‐indoles is described by employing an earth‐abundant nickel‐based catalytic system under air. The notable feature of the present transformation is the use of bench stable and easily affordable polyfluorinated alcohols without any pre‐functionalization for the intro...

Herein, we present an economical method for highly enantioselective and diastereoselective Cu-BINAP-catalysed reductive coupling of alkoxyallenes with a range of electronically and structurally diverse ketones to afford 1,2-syn-tert,sec-diols, using PMHS as the hydride source. This reductive coupling has also been efficiently employed in the enanti...

In recent times, diaryliodonium reagents (DAIRs) have witnessed a resurgence as arylating reagents, especially under photoinduced conditions. However, reactions proceeding through electron donor‐acceptor (EDA) complex formation with DAIRs are restricted to electron‐rich reacting partners serving as donors due to the well‐known cage effect. We disco...

The major impediment in realizing a carbon‐neutral hydrogen fuel economy is the cost and inadequacy of contemporary electrochemical water splitting approaches towards the energy intensive oxygen evolution reaction (OER). The O−O bond formation in the water oxidation half‐cell reaction is both kinetically and thermodynamically challenging and amplif...

Cyclopentenes serve as foundational structures in numerous natural products and pharmaceuticals. Consequently, the pursuit of innovative synthetic approaches to complement existing protocols is of paramount importance. In this context, we present a novel synthesis route for acyl cyclopentenes through a cascade reaction involving an acceptorless-deh...

In recent times, diaryliodonium reagents (DAIRs) have witnessed a resurgence as an arylating agent, especially under photoinduced conditions. However, reactions proceeding through electron donor-acceptor (EDA) complex formation with DAIRs are restricted to electron-rich reacting partners serving as donors due to the well-known cage effect. We disco...

An efficient Rh(II)-catalyzed highly selective N ² -arylation of benzotriazole, indazole, and 1,2,3 triazole is developed using diazonaphthoquinone. The developed protocol is extended with a wide scope. In addition, late-stage arylation of...

An efficient Rh(II)-catalyzed highly selective N2-arylation of benzotriazole, indazole, and 1,2,3 triazole is developed using diazonaphthoquinone. The developed protocol is extended with a wide scope. In addition, late-stage arylation of these scaffolds tethered with bioactive molecules is explored. Control experiments and DFT calculations reveal t...

An organo-photocatalyzed approach for the chemoselective dealkylation and de-esterification of phenols is developed by employing trimethyl silyl chloride as the C‒O bond activator and 9-Mes-10-MeAcr+ClO4‒ as the photoredox catalyst. This method demonstrates an exceptional selectivity towards the cleavage of phenolic ethers and esters over equivalen...

Organosilicons are privileged skeletons in the domains of pharmaceutical chemistry, organic synthesis, and materials science. Hence, investigating catalytic techniques for the synthesis of organosilicon compounds has received a great deal of emphasis. Carbosilylation of alkenes is an efficient technique to introduce diverse molecular architectures...

Designing well-defined Zn-complexes for sustainable dehydrogenative catalysis overcoming the difficulties associated with activating Zn2+(d10)-metal species is considered paramount goal in catalysis. Herein, we explore the plausibility of β-alkylation of secondary alcohols with primary alcohols by well-defined 3d10 Zn-complexes. Detailed organometa...

Increased demand for a carbon-neutral sustainable energy scheme augmented by climatic threats motivates the design and exploration of novel approaches that reserve intermittent solar energy in the form of chemical bonds in molecules and materials. In this context, inspired by biological processes, artificial photosynthesis has garnered significant...

A divergent synthetic approach to access highly substituted indole scaffolds is illustrated. By virtue of a tunable electrochemical strategy, distinct control over the C‐3 substitution pattern was achieved by employing two analogous 2‐styrylaniline precursors. The chemoselectivity is governed by the fine‐tuning of the acidity of the amide proton, r...

We report the Cu(II) catalyzed synthesis of β‐disubstituted ketones from styrene via oxo‐alkylation with unactivated cycloalkanes as the alkylating agent in presence of tert‐butylhydroperoxide (TBHP) and 1‐methylimidazole as oxidant and base respectively. β‐disubstituted ketones are known to be synthesized by using either expensive Ru/Ir complexes,...

An important objective in organic synthesis and medicinal chemistry is the capacity to access structurally varied and complex molecules rapidly and affordably from easily available starting materials. Herein, a protocol for the structurally divergent synthesis of benzofuran fused azocine derivatives and spiro-cyclopentanone benzofurans has been dev...

Water splitting is a potential pathway for hydrogen gas evolution and thereby realization of a carbon‐neutral sustainable energy scheme. However, oxidation of water to dioxygen is the major impediment in conversion of solar energy to fuel. Herein, density functional studies are conducted to explore the reactivity conduits of two molecular electro‐c...

In this work, 1,8-naphthalimide (NMI)-conjugated three hybrid dipeptides constituted of a β-amino acid and an α-amino acid have been designed, synthesized, and purified. Here, in the design, the chirality of the α-amino acid was varied to study the effect of molecular chirality on the supramolecular assembly. Self-assembly and gelation of three NMI...

We disclose a transition-metal-free NaI/PPh3-mediated direct C-H alkylation of azauracils using N-(acyloxy)pthalimides (NHPIs) as readily available alkyl surrogates under visible light irradiation. Detailed mechanistic studies reveal formation of a photoactivated electron donor-acceptor (EDA) complex between NaI/PPh3, TMEDA, and alkyl NHPI ester an...

Molecules with solid state luminescence and mechanochromic luminescence properties have attracted immense interest owing to their potential application in the areas of organic field-effect transistors (OFETs), organic light-emitting diodes (OLEDs), optoelectronic devices, fluorescence switches, mechano-sensors and data storage. Herein we report a c...

A Pd(II)-catalyzed straightforward oxidative naphthylation of unmasked 2-pyridone derivatives is described using a twofold internal alkyne as a coupling partner. The reaction proceeds through N-H/C-H activation to provide polyarylated N-naphthyl 2-pyridones. An unusual oxidative annulation at the arene C-H bond of the diarylalkyne leads to the form...

This study unravels the intricate kinetic and thermodynamic pathways involved in the supramolecular copolymerization of the two chiral dipolar naphthalene monoimide (NMI) building blocks (O-NMI and S-NMI), differing merely by a single heteroatom (oxygen vs sulfur). O-NMI exhibits distinct supramolecular polymerization features as compared to S-NMI...

Helical supramolecular architectures play important structural and functional roles in biological systems. The helicity of synthetic molecules can be tuned mainly by the chiral manipulation of the system. However, tuning of helicity by the achiral unit of the molecules is less studied. In this work, the helicity of naphthalimide-capped peptide-base...

Benzoperylenocarbazole (BPC), a unique carbazole-based organophotocatalyst, is reported herein as a potent organo-photoreductant. Lower excited state oxidation potential (-2.0 V vs SCE) and reasonable excited state lifetime (4.61 ns) render BPC an effective photosensitizer. Under irradiation of blue light employing low catalyst loading (0.5 mol %),...

Merocyanine dye assembly in nonpolar solvents is driven by electrostatic dipole‐dipole interactions, which make hierarchical structures of merocyanine less favorable, due to the compensation of its dipole moment in the discrete antiparallel dimers. Herein, we describe the self‐assembly of a merocyanine dye ( MC‐OH ) into higher aggregates in aqueou...

C≡N bond scission can be a potential avenue for the functionalization of chemical bonds. We have conducted a computational study, using density functional theory (DFT) and ab initio multireference CASSCF methods, to unravel the intricate mechanistic pathways traversed in the copper‐promoted, dioxygen‐assisted reaction for the formation of aryl isoc...

A diastereoselective allylation of N-tert-butane sulfinyl α-iminoesters using allylboronic acids is developed to obtain optically active non-proteinogenic α-amino acid precursors in good yields and diastereoselectivities. Gram-scale synthesis, broad tolerance of functional groups, excellent stereodivergence, post-synthetic modifications, and easy r...

The development of synthetic nonequilibrium systems has gathered increasing attention due to their potential to illustrate the dynamic, complex, and emergent traits of biological systems. Simple building blocks capable of interacting via dynamic covalent chemistry and physical assembly in a reaction network under nonequilibrium conditions can contr...

Stabilizing noncovalently encapsulated guest molecules inside a nanoassembly constructed from amphiphilic polymers has become a very challenging effort in the area of targeted drug delivery of biomedical applications. The unwanted...

The role of solvents in the control over supramolecular interactions has been studied for decades in protein folding, soft material fabrication and long-range organization of functional organic π chromophores. Nonpolar...

A metal-free C-C bond activation strategy of 1,3-diynes has been described via an "extrusion and recombination"approach, which delivered structurally important 1,2-diketones. This phenomenon was performed using tetra-n-butylammonium iodide (TBAI) as a catalyst and peroxide as a radical initiator and oxidant. The C-C bond activation follows sequenti...

b>C≡N bond scission accomplished by protonation, reductive cleavage and metathesis techniques are well-known to execute nitrogen transfer reactions. Herein, we have conducted an extensive computational study, using DFT and molecular dynamics simulations, to unravel the mechanistic pathways traversed in CuCN and CuBr₂ promoted splitting o...

An organophotoredox-catalyzed reduction/addition/oxidation cascade of N-protected maleimides and N-(acyloxy)phthalimides is documented. The mild and efficient redox-neutral process involves hitherto unknown Giese-type addition of aryloxy-alkyl radicals on the N-protected maleimides and a successive oxidation allowing an overall Z-alkenylation of N-...

Density functional calculations have been performed to elucidate the mechanism of formation of N‐phenylbenzylamine (Am) from alkylation of aniline (An) with benzaldehyde (Bz), with the intermediacy of the imine, N‐benzylideneaniline (Im), catalyzed by the triaryl borane (BAr3), B(2,6‐Cl2C6H3)(p‐HC6F4)2, and utilizing H2 as the reductant. Our comput...

Conversion of CO2 into liquid fuels and value-added fine chemicals has gained much attention in recent years to meet the ever-rising global energy demand and hence develop a sustainable solar fuel economy. This chapter enumerates feasible catalytic routes through which CO2 could be utilized as a C1 feedstock. First, we address CO2 functionalization...

The conversion of CO2 into liquid fuels and value-added fine chemicals is of significant interest for both environment and global energy demand. In this frontier article, we highlight viable methods for transforming CO2 into valuable C1 feedstocks and summarize the key mechanistic aspects obtained by in-depth computational investigations of three i...

Catalytic removal of H2 from boron‐nitride (BN)‐based nanomaterials at ambient conditions is of paramount importance in order to develop lightweight hydrogen storage media. Here, the DLPNO‐CCSD(T) technique is used to calculate accurate relative energies and activation barriers of Brønsted acid‐initiated removal of H2 from hydrogenated BN nanotubes...

Post-synthetic modification of organic linkers embedded in a metal–organic framework (MOF) is a favourable strategy to improve the storage of hydrogen through physisorption at ambient conditions. Density functional and domain-based local pair natural orbital coupled cluster calculations are conducted to evaluate the feasibility of hydrogen adsorpti...

Supra-amphiphiles constituted of non-covalent bonds have emerged as attractive systems for fabrication of stimuli-responsive self-assembled nanostructures. A unique supramolecular strategy utilizing halogen (X)-bonding interaction has been demonstrated for constructing emissive supra-π-amphiphiles in water from a hydrophobic pyridyl functionalized...

Selective functionalization of C−H bonds provides a straightforward approach to a large variety of well‐defined derivatives. High‐valent mononuclear iron(IV)‐oxo complexes are proposed to carry out these C−H activation reactions in enzymes or in biomimetic syntheses. In this Minireview, we aim to highlight the features that delineate the distinct r...

Fixation and chemical reduction of CO 2 are important for utilization of this abundant resource, and understanding the detailed mechanism of CO cleavage is needed for rational development of CO 2 reduction methods. Here, we describe a detailed analysis of the mechanism of the reaction of a masked two-coordinate cobalt(I) complex, L tBu Co (where L...

Selective C=C bond oxidation is a fundamental process in Nature and has potential utility in organic synthesis. Herein, we employ ab initio and density functional techniques to investigate the nature of the oxidant and mechanism in alkene oxidation by two H2O2 activating Rieske oxygenase inspired iron catalysts, one of which is more sterically encu...

We employ quantum chemical calculations to study the hydrogenation of carbon dioxide by amine boranes, NMe3BH3(Me3AB) and NH3BH3(AB) weakly bonded to a bulkier Lewis acid, Al(C6F5)3(LA). Additionally, computations have also been conducted to elucidate the mechanism of hydrogenation of carbon dioxide byMe3AB while captured between one Lewis base (P(...

Ligand exchange plays an important role in the biogenesis of Fe/S clusters, most prominently during cluster transfer from a scaffold protein to its target protein. Although in?vivo and in?vitro studies have provided some insight into this process, the microscopic details of the ligand exchange steps are mostly unknown. In this work, the kinetics of...

Multiple-bonded iron-oxo and -nitrido species have been identified or proposed as key intermediates in a range of important chemical transformations. The reported model complexes feature various coordination geometries and distinct electronic structures, and therefore exhibit diverse reactivity. The present contribution highlights the synergy from...

The role of pendant boron ligands in ammonia-borane (AB) dehydrogenation have been investigated using hybrid density functional theory for two very efficient Ruthenium based catalysts, developed by Williams and co-workers (J. Am. Chem. Soc. 2011, 133, 14212–14215). Our findings reveal that the catalytic action initiates through opening of the labil...

Oxidation by dioxygen has a rich repertoire of mechanistic intricacies. Herein, we report a hitherto unknown paradigm of dioxygen activation reaction which propagates through a 4 center 2 electron (4c-2e) bound species. Using static DFT and ab initio quantum chemical techniques we have unraveled the oxidation pathway for hydrazine and its methylate...

Through carefully calibrated density functional studies we predict that Ir pincer complexes, previously known to effectuate simultaneous proton and hydride transfer from ammonia-borane at ambient conditions, are equally efficient catalysts for the concerted dehydrogenation and subsequent release of H2 from hydrogenated boron nitride nanotubes overc...

Chemisorbed hydrogen on boron nitride nanotubes (BNNT) can only be released thermally at very high temperatures above 350 °C. However, no catalyst has been identified that could liberate H2 from hydrogenated BN nanotubes under moderate conditions. Using different density functional methods we predict that the desorption of chemisorbed hydrogen from...

Self-assembly of a series of carboxylic acid-functionalized naphthalene diimide (NDI) chromophores with a varying number (n=1-4) of methylene spacers between the NDI ring and the carboxylic acid group has been studied. The derivatives show pronounced aggregation due to the synergistic effects of H-bonding between the carboxylic acid groups in a syn...

We have conducted a hybrid density functional study to explore the mechanism of oligo-polymerization of aminoborane, NH2BH2 formed immediately after dehydrogenation of NH3BH3 (Ammonia borane) both in nucleophilic and non-nucleophilic solvent medium. We find that the nucleophilicity of donor solvents and an in-situ generated intermediate, B-(cyclodi...

Chemical hydrogen storage: Theoretical investigations showed that the dehydrogenation of chemisorbed hydrogen atoms on boron nitride nanotubes (BNNT) could be triggered by appropriate reagents through simultaneous proton and hydride transfer. The computed free-energy of the activation barrier for the reduction of formaldehyde to methanol by chemiso...

The chameleon reductant: CO2 trapped by a frustrated Lewis pair is predicted to undergo BH activation mediated reduction by NH3BH3, in contrast to concerted NH3BH 3 reduction of free CO2 (see figure). This mechanism provides further fundamental understanding of novel CO2 reduction processes that could lead to environmentally friendly and economi...