Faculty Publications
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Publications by NITK Faculty
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Item Copper-catalyzed aerobic annulation of hydrazones with dienones: an efficient route to pyrazole-linked hybrid molecules(Royal Society of Chemistry, 2024) Nayak, K.H.; Jijin, R.K.; Sreelekha, M.K.; Babu, B.P.A copper-catalyzed aerobic [3 + 2] annulation reaction to access various pyrazole-bound chalcones starting from readily available and cost-effective hydrazones and dienones is reported. These pyrazole-bound chalcones were further utilized effectively to prepare a series of pyrazole-linked hybrid molecules, such as pyrazole-pyrazoline, pyrazole-aziridine, and pyrazole-pyridine hybrids by efficient simple transformations. Synthetically challenging hybrid molecules were obtained in a simple, two-step process with high atom economy under aerobic copper catalysis. © 2024 The Royal Society of Chemistry.Item Base-promoted multicomponent synthesis of 1,2,4-triazole-based hybrids from 1,3-diones, β-nitrostyrenes, and hydrazones(Royal Society of Chemistry, 2024) Sreelekha, M.K.; Jijin, R.K.; Nayak, K.H.; Babu, B.P.Herein, we report a metal-free, base-promoted route for the synthesis of hybrid molecular scaffolds in which various 1,3-diones and 1,2,4-triazoles are linked by a benzyl bridge. This three-component, one-pot reaction was accomplished by first treating 4-hydroxycoumarin, trans-β-nitrostyrene, and aldehyde hydrazone in the presence of sodium carbonate. Further, this protocol was successfully expanded to other 1,3-diones, such as dimedone and 4-hydroxy-2-quinolone. A broad substrate scope, mild reaction conditions, and the metal and ligand/additive-free approach are the prominent features of this strategy. © 2024 The Royal Society of Chemistry.Item In Situ Generation and [3 + 2] Annulation Reactions of Propiolaldehyde?A Metal-Free, Cascade Route to Pyrazole and Bipyrazole Carboxaldehydes in One Pot(American Chemical Society, 2025) Sreelekha, M.K.; Shamnad, A.; Bhaskaran, R.P.; Babu, B.P.Propiolaldehyde, the most reactive yet less explored electrophilic acetylene, was generated in situ via a base-free Kornblum oxidation from propargyl tosylate and successfully intercepted with hydrazones affording pyrazole-4-carboxaldehyde in one-pot by a [3 + 2] annulation reaction. Further, the pyrazole-4-carboxaldehyde endured a unique cascade reaction with phenylhydrazine and propargyl tosylate, yielding synthetically challenging bipyrazole carboxaldehydes. The method is free of any metal catalyst, base, or additives and offers a convenient protocol to handle the reactive and volatile propiolaldehyde under ambient conditions. © 2025 American Chemical Society.