BITS Faculty Publications
Permanent URI for this communityhttp://localhost:4000/handle/123456789/1867
Browse
195 results
Search Results
Item Inherent weakly coordinating oxo-group-directed ruthenium(ii)-catalyzed C5 functionalization of 2-arylquinolin-4(1h)-ones(ACS, 2025) Kumar, AnilA Ru(II)-catalyzed inherent weakly coordinating oxo-group-directed site-selective C5 functionalization of 2-arylquinolin-4(1H)-ones using various coupling partners like allyl alcohols, acrylates, styrenes, maleimides, and acrylamide has been described. The developed method allowed the synthesis of C5-substituted 2-arylquinolin-4(1H)-ones in good to excellent yields. The protocol is compatible with a broad range of functional groups and can be used on the gram scale. In addition, based on the control experiments, a plausible reaction mechanism has been proposed for this transformation.Item Propargyl alcohol as an acrolein equivalent: synthesis of β-(3-indolyl)acroleins and β-(imidazo[1,2-a]pyridin-3-yl)acroleins(RSC, 2024-09) Kumar, AnilA simple and straightforward method has been developed to access distinctly substituted β-(3-indolyl)acroleins and β-(imidazo[1,2-a]pyridin-3-yl)acroleins using propargyl alcohol as an acrolein equivalent. A broad substrate scope, good yields, easily accessible substrates, and metal-free conditions are the salient features of the developed methodology. This work contributes to a significant advancement in the sustainable synthesis of functionalized acroleinsItem RU(ii)-catalyzed [4 + 2]-annulation of 2-alkenyl/arylimidazoles with N-substituted maleimides and 1,4-naphthoquinones: access to imidazo-fused polyheterocycles(ACS, 2024-02) Kumar, AnilSynthesis of imidazo-fused polyheterocyclic molecular frameworks, viz. imidazo[1,2-a]pyrrolo[3,4-e]pyridines, imidazo[2,1-a]pyrrolo[3,4-c]isoquinolines, and benzo[g]imidazo[1,2-a]quinoline-6,11-diones, has been achieved by the ruthenium(II)-catalyzed [4 + 2] C–H/N–H annulation of 2-alkenyl/2-arylimidazoles with N-substituted maleimides and 1,4-naphthoquinones. The developed protocol is operationally simple, exhibits broad substrate scope with excellent functional group tolerance, and provides the desired products in moderate to good yields. The mechanistic studies suggest that the reaction involves the formation of a C–C bond through Ru-catalyzed C(sp2)–H bond activation followed by intramolecular cyclizationItem Recent advances in metal-catalyzed approaches for the synthesis of quinazoline derivatives(MDPI, 2024-05) Kumar, AnilQuinazolines are an important class of heterocyclic compounds that have proven their significance, especially in the field of organic synthesis and medicinal chemistry because of their wide range of biological and pharmacological properties. Thus, numerous synthetic methods have been developed for the synthesis of quinazolines and their derivatives. This review article briefly outlines the new synthetic methods for compounds containing the quinazoline scaffold employing transition metal-catalyzed reactions.Item Visible light-driven difluoroalkoxylation of imidazopyridines using n-fluorobenzenesulfonimide as fluorinating agent(Wiley, 2024-08) Kumar, AnilA visible-light-promoted site-selective difluoroalkoxylation of imidazo[1,2-a]pyridines has been achieved using N-fluorobenzenesulfonimide (NFSI) as a fluorinating agent. This practical reaction has a wide range of substrate scope for both imidazo[1,2-a]pyridines and alcohols to give 3,3-difluoro-2-alkoxy-2-arylimidazo[1,2-a]pyridines in 65–93% yields. The reaction proceeded at room temperature, showed high functional group tolerance, and was amenable to scale-up. Based on mechanistic investigation, a radical pathway is proposed.Item Ru(II)-catalyzed oxidative (4+3) C–H/C–H annulation of 2-aryl-4H-pyrido[1,2-a]pyrimidin-4-ones with allyl alcohol(RSC, 2025-03) Kumar, AnilA ruthenium(II)-catalyzed direct oxidative (4+3) C–H/C–H annulation of 2-aryl-4H-pyrido[1,2-a]pyrimidin-4-ones with allyl alcohol has been described. The developed method yielded the corresponding annulated products in moderate to good yields. In addition, based on the control experimental results, a possible reaction mechanism has been proposed for the (4+3) C–H/C–H annulation reaction.Item Tempo-mediated direct C(SP2)–H alkoxylation/aryloxylation of 1,4-quinones(ACS, 2025-01) Kumar, AnilA convenient and efficient transition-metal-free method has been developed for the C(sp2)–H alkoxylation/aryloxylation of 1,4-quinones by direct cross-dehydrogenative coupling with readily available alcohols and phenols in the presence of TEMPO under simple and mild conditions. The method allowed the installation of a wide range of alkoxy/aryloxy groups, exhibited high functional group tolerance, showed a broad substrate scope, afforded good to excellent yields of products in a simple one-pot operation, and could be performed on a gram scale. Mechanistic investigation indicated the involvement of the radical pathway.Item Ruthenium(ii)-catalyzed C−H/C−H(4+2) annulation of 2-aryl-N-heterocycles with vinylene carbonate(Wiley, 2024-11) Kumar, AnilA ruthenium(II)-catalyzed direct C−H/C−H (4+2) annulation of 2-aryl-N-heterocycles such as 2-aryl-4H-pyrido[1,2-a]pyrimidin-4-ones, 2-arylimidazo[1,2-a]pyridines, 2-aryl-2H-indazoles and 2-arylquinolin-4(1H)-ones with vinylene carbonate has been described. This one-pot cascade strategy provided the diversely substituted fused-polyheterocycles such as 7H-benzo[h]pyrido[2,1-b]quinazolin-7-ones, naphtho[1′,2′:4,5]imidazo[1,2-a]pyridines, indazolo[2,3-a]quinolines and benzo[c]acridin-7(12H)-ones in moderate to excellent yields. The developed protocol exhibited a broad substrate scope with good functional group tolerance and acid/base-free conditions. Based on a preliminary mechanistic investigation, a tentative mechanism of Ru(II)-catalyzed (4+2) annulation reaction has been proposed.Item Unsymmetrical nne (e = s, se) pincer palladium(ii) complexes: syntheses, structure, and catalytic activity in decarboxylative heteroarylation of coumarin-3-carboxylic acids(ACS, 2025-04) Roy, Ram Kinkar; Kumar, AnilThis report describes the syntheses of two novel benzoxazolyl-derived unsymmetrical NNE (E = S, Se) pincer ligands and their palladium(II) complexes. Treatment of benzoxazolyl-derived pincer ligands L1 and L2 with PdCl2(CH3CN)2 provided complexes C1 and C2, respectively, in which the NNE ligands coordinated to Pd in a tridentate pincer manner. The ligands and complexes were characterized by 1H and 13C Nuclear Magnetic Resonance (NMR), Fourier-transform infrared spectroscopy (FTIR), high-resolution mass spectrometry (HRMS), UV–visible, X-ray photoelectron spectroscopy (XPS), and cyclic voltammetry techniques. The structure of the ligand and its coordination mode with the palladium center was established using a single-crystal X-ray diffraction technique. The complex C2 showed a pincer coordination mode with a distorted square planar geometry. The catalytic performance of palladium complexes C1 and C2 was investigated for the decarboxylative heteroarylation of coumarin-3-carboxylic acid. Notably, heteroarenes could give up to 80% of heteroarylation products in the presence of 5 mol % of the catalyst. A broad substrate of heteroarenes showed tolerance toward the developed protocol. Among complexes, the selenium ligand coordinated complex (C2) outperformed the sulfur ligand coordinated complex C1, which may be due to stronger σ-donation by the Se atom.Item Advances in transition metal‐catalyzed C(sp2)–H bond functionalization using allyl alcohols(Wiley, 2025-03) Kumar, AnilThe transition metal-catalyzed directed site-selective C─H bond functionalization utilizing allyl alcohols as coupling partner has been an intriguing area of research and has made considerable advances during the past decade. Multifunctional coupling characteristics of the allyl alcohol in the regioselective C(sp2)–H functionalization using transition metal-catalysis produces alkyl, alkenyl, allyl, and annulated products. These reactions provide an effective synthetic tool to afford diverse functionalized scaffolds that are of interest in synthetic and medicinal sciences. This review covers the developments of directed site-selective C(sp2)–H functionalization with unactivated allyl alcohols as the coupling partner using the transition metal-catalysis till December, 2024.