N. Bakthavatchala Reddy

Green Synthesis of Aminobisphosphonates Under Microwave Irradiation

Abstract A simple, efficient, and environmentally benign green chemical method has been developed for the synthesis of aminobisphosphonates by reacting aliphatic/aromatic 2°-amines, dimethylphosphite, and triethylorthoformate by microwave irradiation under solvent-free conditions, in the presence of an alumina solid support. The advantages of this method are less reaction time, simple work-up, and excellent yields. Supplemental materials are available for this article. Go to the publishers online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file. GRAPHICAL ABSTRACT

The Synthesis and Bioactivity of Dimethyl (2,3- Dihydrobenzo[b][1,4]Dioxin-6-Yl)(Aryl Amino)Methylphosphonates

Abstract A new series of α-aminophosphonates have been synthesized by a one-pot three-component reaction of 2,3-dihydrobenzo[b][1,4]dioxine-6-carbaldehyde, various amines, and dimethyl phosphite by using nano-TiO2 as a catalyst under solvent-free conditions at 50°C. The major advantages of the present method are high yields, short reaction times, recyclable catalyst, and solvent-free reaction conditions. Among these new structurally diversified set of α-aminophosphonates, dimethyl (2,3-dihydrobenzo[b][1,4]dioxin-6-yl)(3-nitrophenylamino) methylphosphonate and dimethyl (2,3-dihydrobenzo[b][1,4]dioxin-6-yl)(4-fluoro-3-nitro-phenyl-amino) methylphosphonate have shown higher antioxidant activity in diphenyl picryl hydrazyl (DPPH) scavenging, reducing power assay, and lipid peroxidation methods. GRAPHICAL ABSTRACT

Designing, synthesis, and characterization of some novel coumarin derivatives as probable anticancer drugs

Coumarin is a naturally occurring oxygen heterocyclic having multifarious medicinal properties, hence used as a lead compound for designing new potent analogs. Based on the X-ray crystal structure of complexes of inhibitors containing coumarin nucleus with human NAD(P)H:quinone oxidoreductase-1 and human phosphodiesterase 4B enzymes, some novel coumarin derivatives have been designed as probable inhibitors specifically for pancreatic cancer. These two enzymes are overexpressed in various tumors, the former specifically in pancreatic cancer. The computational analysis by e-pharmacophore and docking studies suggested that specific groups at position 8 of 4-methyl-7-hydroxycoumarin have anticancer activity against skin cancer in mice and can enhance the anti-tumor activity. The chemical syntheses of 4-methyl-7-hydroxycoumarin and its 8-formyl derivative were carried out using Pechmann’s condensation followed by Duffs reaction. Treatment of the 8-formyl derivative with nine different N,N-di substituted cyanoacetamides in the presence of piperidine afforded the corresponding nine new 8-substituted-4-methyl-7-hydroxycoumarin derivatives. These compounds were characterized by IR, 1H, 13C NMR, mass spectra and elemental analysis. Intriguingly, molecular docking suggested a remarkable binding pose for all the nine coumarin derivatives vis-a-vis coumarin itself, opening further options for designing inhibitors for tumor suppression. From the docking simulation study, it was concluded that the derived coumarin derivatives are active against more than one proteins and most importantly addition of substituents at the 8th position of 4-methyl-7-hydroxycoumarin support the possibility of new coumarin derivatives having comparatively higher binding affinity and therefore more potent inhibitors.

Ionic Liquid–Promoted Phospha-Michael Reaction: Convenient Access to β-Nitrophosphonates

Abstract A convenient and mild procedure is developed for β-nitrophosphonates via phospha-Michael addition of phosphites to nitrostyrene at room temperature in the presence of 1,8-diazabicyclo-[5.4.0]undec-7-ene (DBU)–based ionic liquid [DBUH][OAc]. The operational simplicity, convenient workup, and reusability of the ionic liquid make this method attractive. GRAPHICAL ABSTRACT

Synthesis and Bioassay of Ethyl-2- (2-((Diethoxyphosphoryl) (Aryl) Methylamino)Thiazol-4-Yl)-2-(Methoxyimino)Acetates

Abstract A simple, efficient, and environmentally benign methodology has been accomplished for the synthesis of α-aminophosphonates by one-pot three-component reaction of ethyl-2-amino-α-(methoxy-imino)-4-thiazoleacetate, aldehydes, and diethylphosphite by using Amberlyst-15 as catalyst at room temperature under solvent-free conditions. Their chemical structures were characterized by infrared (IR), NMR (1H, 13C & 31P), mass spectral, and elemental analysis. All the title compounds were screened for radical-scavenging activity by 1,1-diphenyl-2-picrylhydrazyl (DPPH), nitic oxide (NO), and hydrogen peroxide (H2O2) methods. Supplementary materials are available for this article. Go to the publishers online edition of Phosphorus, Sulfur, and Silicon and the Related Elements for the following free supplemental files: Additional text and figures. GRAPHICAL ABSTRACT