M. B. Madhusudana Reddy

Glycine-Catalyzed Efficient Synthesis of Pyranopyrazoles via One-Pot Multicomponent Reaction

A facile and convenient protocol is developed for the fast (5–20 min) and high-yielding (85–95%) synthesis of fused pyranopyrazoles from ethyl acetoacetate, hydrazine hydrate, an aldehyde, and malononitrile in the presence of nontoxic, simple, and readily available organocatalyst glycine in aqueous medium at 25 °C.

Molecular Iodine–Catalyzed, Mild, Effective, Ecofriendly, Microwave-Assisted, One-Pot Synthesis of 5-Arylmethylidene-2-phenyloxazol-4-ones (Azalactones) Under Solvent-Free Conditions

Fourteen azalactones have been synthesized in excellent yields under solvent-free conditions by heating an aldehyde, hippuric acid, and acetic anhydride in the presence of molecular iodine as a catalyst in a microwave oven. The short reaction time, cleaner reaction, and easy workup make this protocol practical and economically attractive.

Efficient Method of Synthesis of N,N′-Disubstituted Ureas/Thioureas by a Zinc Chloride Catalyzed Thermal Reaction

Abstract Symmetrically N,N′-disubstituted ureas/thioureas were synthesized by heating amines or phenyl hydrazine and urea/thiourea on a preheated hot plate at 80–85°C under solvent-free conditions in the presence of a catalytic amount of ZnCl2 as a catalyst. The protocol has the advantages of not using toxic phosgene and other hazardous substrates or organic solvents. Increased reaction rate, good yield, and a simple workup procedure are involved.

Iodine-Catalyzed Versatile Synthesis of 4,6-Diarylpyrimidin-2(1H)-ones (DAPMs) via One-Pot, Multicomponent Reaction

Abstract An efficient, solvent-free, one-pot, three-component cyclocondensation reaction between aldehyde, ketone, and urea to give 4,6-diarylpyrimidin-2(1H)-ones (DAPMs) using iodine as catalyst is described. This new protocol provides a simple and environmentally benign route along with the associated advantages of good to excellent yield of the products (90–96%) and short reaction times (5–15 min) at 80 °C.

Synthesis of one-dimensional gold nanostructures and the electrochemical application of the nanohybrid containing functionalized graphene oxide for cholesterol biosensing.

This manuscript reports a new approach for the synthesis of one dimensional gold nanostructure (AuNs) and its application in the development of cholesterol biosensor. Au nanostructures have been synthesized by exploiting β-diphenylalanine (β-FF) as an sacrificial template, whereas the Au nanoparticles (AuNPs) were synthesized by ultrasound irradiation. X-ray diffractometer (XRD), scanning electron microscope (SEM) and energy dispersive analysis of X-rays (EDAX) have been employed to characterize the morphology and composition of the prepared samples. With the aim to develop a highly sensitive cholesterol biosensor, cholesterol oxidase (ChOx) was immobilized on AuNs which were appended on the graphite (Gr) electrode via chemisorption onto thiol-functionalized graphene oxide (GO-SH). This Gr/GO-SH/AuNs/ChOx biosensor has been characterized using cyclic voltammetry (CV), electrochemical impedance spectroscopy and chronoamperometry. CV results indicated a direct electron transfer between the enzyme and the electrode surface. A new potentiostat intermitant titration technique (PITT) has been studied to determine the diffusion coefficient and maxima potential value. The proposed biosensor showed rapid response, high sensitivity, wide linear range and low detection limit. Furthermore, our AuNs modified electrode showed excellent selectivity, repeatability, reproducibility and long term stability. The proposed electrode has also been used successfully to determine cholesterol in serum samples.

Unconstrained Homooligomeric gamma-Peptides Show High Propensity for C-14 Helix Formation

Monosubstituted γ(4)-residues (γ(4)Leu, γ(4)Ile, and γ(4)Val) form helices even in short homooligomeric sequences. C14 helix formation is established by X-ray diffraction in homooligomeric (γ)n tetra-, hexa- and decapeptide sequences demonstrating the high propensity of γ residues, with proteinogenic side chains, to adopt locally folded conformations.

Zn(OAc)2 · 2H2O-Catalyzed, Simple, and Clean Procedure for the Synthesis of 2-Substituted Benzoxazoles Using a Grindstone Method

Abstract Zn(OAc)2 · 2H2O efficiently catalyzes the condensation reaction between 2-aminophenol and various araldehydes to afford the 2-substituted benzoxazoles in good to excellent yields. The remarkable features of this protocol are simple and mild reaction conditions, use of readily available catalyst, and shorter reaction time, and in addition the reaction proceeds just by grinding the substrates and catalyst without any solvent and hence matches the green chemistry protocols.

Iodine-Catalyzed, Efficient, One-Pot Protocol for the Conversion of Araldehydes into 5-Aryl-1H-tetrazoles

Abstract An easy access to various 5-aryl-1H-tetrazoles by a one-pot direct conversion of aldehydes to tetrazoles without the isolation of the intermediate nitriles using commercially available iodine as a catalyst is described. The protocol offers advantages in terms of good yields, mild reaction conditions, short reaction times, and use of readily available environmentally compatible catalyst.

Efficient and High-Yielding Protocol for the Synthesis of Nitriles from Aldehydes

An operationally simple and high-yielding procedure has been developed for the conversion of araldehydes into the corresponding nitriles using p-toluenesulfonic acid (p-TSA) (a mild catalyst) under microwave irradiation. The products are characterized by infrared spectral analysis and by comparison of the melting and boiling points with the reported values.

Molecular Iodine–Catalyzed Mild and Effective Synthesis of β-Enaminones at Room Temperature

Abstract Molecular iodine has been found to be an efficient and ecofriendly catalyst for the synthesis of β-enaminones from dimedone and amines at room temperature in the presence of acetonitrile within 60 min. The experimental procedure is simple, includes shorter reaction times, and results in excellent yields of the products.