Mudumala Veeranarayana Reddy

Polymer grafted layered double hydroxides (LDHs-g-POEGMA): a highly efficient reusable solid catalyst for the synthesis of chromene incorporated dihydroquinoline derivatives under solvent-free conditions

A novel poly(oligoethylene glycol methacrylate)-g-supported layered double hydroxides (LDHs-g-POEGMA) with high surface area with easy accessibility of active sites was successfully prepared for the first time via an efficient sequential synthetic procedure and characterized by FT-IR spectroscopy, XPS spectra, thermogravimetric analysis (TGA), powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and NMR spectroscopy. The obtained green catalyst was used as an effective, inexpensive, environmentally friendly, and highly active reusable heterogeneous solid catalyst for synthesis of chromene incorporated dihydroquinoline derivatives via a one-pot three-component condensation of 4-hydroxy-2H-chromen-2-one, aromatic amines, and various aldehydes under solvent-free conditions. The notable features of this “green” reaction are good to excellent yields, shorter reaction times, avoidance of toxic solvents, and substrate diversity. Herein we also observed that the LDHs-g-POEGMA is highly stable under reaction conditions and can be separated easily from the reaction mixture, and, therefore, can be reused for several consecutive runs without any apparent loss in its catalytic activity.

Ultrasound-assisted one-pot synthesis of 1,3-oxazine derivatives catalysed by BF 3 –SiO 2 under neat conditions

An efficient and environment-friendly method for the synthesis of 1,3-oxazine derivatives has been developed using the ultrasound-mediated condensation of 2-naphthol with formaldehyde and primary amines under solvent-free condition at room temperature in the presence of BF3-SiO2 to give the desired product in good to excellent yield. This procedure provides several advantages over current methods including a simple work-up, cost effectiveness, a reusable catalyst and shorter reaction times.

Chlorosulfonic acid supported diethylamine ionic liquid catalyzed green synthesis of novel 2-mercaptonaphthalen-1-yl)methyl)-3-hydroxy-5,5-dimethylcyclohex-2-enones under neat conditions

Chlorosulfonic acid supported diethylamine ionic liquid (DEACSA IL) was prepared and characterized by FT-IR, elemental analysis, NMR spectroscopy and thermogravimetric analysis. The DEACSA IL functions as an efficient heterogeneous, environmentally benign, and very active catalyst and can be recycled for several runs without any significant loss of activity with short reaction times, good to excellent yields of the desired products and high catalytic activity for the synthesis of a variety of novel 2-mercaptonaphthalen-1-yl)methyl)-3-hydroxy-5,5-dimethylcyclohex-2-enones under neat conditions. This is the first example of the condensation of naphthalene-2-thiol, aldehydes and 5,5-dimethylcyclohexane-1,3-dione to provide a novel series of thiol derivatives, which were characterized by 2D-NMR data.

A highly efficient and recyclable molybdate sulfuric acid (MSA) catalyst for the synthesis of dimethyl (2,3-dihydro-1H-inden-6-ylamino) (substituted) methylphosphonates under microwave irradiation

An efficient green synthesis of dimethyl (2,3-dihydro-1H-inden-6-ylamino) (substituted) methylphosphonates has been achieved under solvent-free conditions by the reaction of 2,3-dihydro-1H-inden-5-amine, aldehydes and ethyl dimethyl phosphonate by microwave irradiation in the presence of molybdate sulfuric acid (MSA) as a catalyst. High product yields in shorter reaction times, easy isolation of products, reusability of solid catalysts and environmentally benign reaction conditions are its advantages.

Molybdate sulfuric acid (MSA): an efficient reusable catalyst for the synthesis of tetrahydrobenzo[4,5]imidazo[2,1-b]quinazolin-1(2H)-ones under solvent-free conditions and evaluation of their in vitro bioassay

An efficient green synthesis of tetrahydrobenzo[4,5]imidazo[2,1-b]quinazolin-1(2H)-ones has been achieved under solvent-free conditions by the reaction of 1H-benzo[d]imidazol-2-amine, various aldehydes and 1,3-dicarbonyl compounds in the presence of molybdate sulfuric acid (MSA) as a catalyst. Higher product yields were isolated easily using this reusable MSA catalyst, and environmentally benign reaction conditions in shorter reaction time are the merits of this reaction. All the newly synthesized compounds were tested for their anti-oxidant and anticancer activities. Most of them showed good to excellent bio-activity in both the experiments.

Di- n -butyl ammonium chlorosulfonate ionic liquids as an efficient and recyclable catalyst for the synthesis of 1,4-dihydrobenzo[4,5]imidazo[1,2-a]pyrimidine-3-carboxylates under solvent-free ultrasound irradiation

Abstract In this study, we present a straightforward, efficient and convenient approach for the synthesis of medicinally important 1,4-dihydrobenzo[4,5] imidazo [1,2-a]pyrimidine-3-carboxylates via three-component reactions of aldehydes, 1H-benzo[d]imidazol-2-amine and active methylene compounds in the presence of di-n-butyl ammonium chlorosulfonate ionic liquids (DBA IL) under ultrasound irradiation. This process develops the synthetic potential of ultrasound irradiation with DBA IL combination and presents much compensation, such as outstanding product yields, reusable catalyst, less reaction periods, gainful cost, easy work-up/purification and environmentally benign reaction conditions. Graphical AbstractThe attractive features of this methodology are simple procedure, green reaction, reusability and high efficiency of the catalyst, and easy workability.

Silica sodium carbonate: the most efficient catalyst for the one-pot synthesis of indeno[1,2- b ]quinoline and spiro[chromene-4,3′-indoline]-3-carbonitriles under solvent-free condition

A new silica sodium carbonate-assisted convenient and efficient strategy for the synthesis of indeno[1,2-b]quinoline and spiro[chromene-4,3′-indoline]-3-carbonitriles derivatives in solvent-free media is described. The reactions can be performed at low catalyst loadings with excellent functional group tolerance. The catalyst can be easily recovered and reused for the next reaction for at least three runs without any significant impact on the yields of the products. The easy recovery of the catalyst and high yield of the products make the protocol attractive, sustainable, and economic.Graphical abstract

Silica tungstic acid (STA) as a highly efficient and reusable catalyst for the synthesis of benzoxanthenes under solvent-free conditions in ultrasonication

An environmentally benign, ultrasound-promoted synthesis of biologically active benzoxanthene derivatives has been developed by silica-supported tungstic acid as an efficient catalyst under solvent-free conditions. The major advantages of the present protocol are operational simplicity, use of an inexpensive catalyst, bypassing the chromatographic purification, good yields, and short reaction times. The catalyst could be reused at least five consecutive cycles, without loss of its catalytic activity.

Copper(II) oxide nanoparticles as a highly active and reusable heterogeneous catalyst for the construction of phenyl-1H-pyrazolo[3,4-b]pyridine derivatives under solvent-free conditions

An efficient, highly active and resalable copper oxide nanoparticle catalyzed a regioselective cascade synthesis of phenyl-1H-pyrazolo[3,4-b]pyridine derivatives via three-component domino reactions of aldehydes, alkynes and 3-methyl-1-phenyl-1H-pyrazol-5-amine under solvent-free conditions. Good to excellent yield, short reaction times, cost effectiveness; environmental friendliness, easy workup, and a recyclable catalyst are the important features of this protocol. This is the first endeavor towards the synthesis of phenyl-1H-pyrazolo[3,4-b]pyridine derivatives from 3-methyl-1-phenyl-1H-pyrazol-5-amine, alkynes and aldehydes.