Synthesis of novel proline-thiazole based cyclic hexa- and octapeptides

Novel proline-thiazole based cyclopeptides were produced by cyclooligomerisation of an L-proline thiazole amino acid HCl in the presence of pentafluorophenyl diphenylphosphinate (FDPP) or diphenyl phosphorazidate (DPPA).     

Phosphosulfonic acid‐catalyzed green synthesis and bioassay of α‐aryl‐α′‐1,3,4‐thiadiazolyl aminophosphonates

A series of new α‐aminophosphonates containing 1,3,4‐thiadiazole moiety (4a–l) were synthesized via a simple, efficient, and one‐pot three‐component Kabachnik–Fields reaction of 2‐amino‐5‐ethyl‐1,3,4‐thiadiazole with various aryl/heteroaryl aldehydes and diethylphosphite under solvent‐free microwave irradiation conditions using phosphosulfonic acid, as a reusable and heterogeneous solid acid catalyst. All the title compounds were screened for radical scavenging activity by DPPH and H₂O₂ methods, and antimicrobial activity against bacteria (Gram‐positive and Gram‐negative) and fungi using the disc diffusion technique. They exhibited potent in vitro antioxidant and moderate antimicrobial activity.     

Nano Gd2O3 catalyzed synthesis and anti-oxidant activity of new α-aminophosphonates

A one pot three-component nano Gd₂O₃ catalyzed neat reaction of 2-morpholinoethanamine and dimethylphosphite with various salicylaldehydes under microwave irradiation afforded a series of new α-aminophosphonates in high yields. The synthesized compounds were characterized by FT-IR, (¹H, ¹³C, ³¹P)-NMR, and mass spectral methods. The antioxidant activity of these compounds was evaluated against DPPH, NO, and H₂O₂ methods and found that the compound Dimethyl (2-hydroxy-5-nitrophenyl) (2-morpholinoethylamino) methylphosphonate (4h) has higher antioxidant activity than the corresponding standards.     

A note on the dispersion of Love waves in layered monoclinic elastic media

The dispersion equation for Love waves in a monoclinic elastic layer of uniform thickness overlying a monoclinic elastic half-space is derived by applying the traction-free boundary condition at the surface and continuity conditions at the interface. The dispersion curves showing the effect of anisotropy on the calculated phase velocity are presented. The special cases of orthotropic and transversely isotropic media are also considered. It is shown that the well-known dispersion equation for Love waves in an isotropic layer overlying an isotropic half-space follows as a particular case.     

Palladium acetate-catalysed one-pot green synthesis of bis α-aminophosphonates

Research on Chemical Intermediates - A simple and effective green method has been developed for the synthesis of a series of novel bis α-aminophosphonate derivatives (4a–j) by the...     

Synthesis of β‐Arylacyl/β‐Heteroarylacyl‐β‐alkylidene Malonates and Their Application in Substituted Pyridone Synthesis

A novel approach has been developed for the synthesis of β‐arylacyl/β‐heteroarylacyl‐β‐alkylidine malonates in moderate to good yields by the reaction of Stork aryl and heteroaryl enamine with β‐chloroalkylidene malonates. The reaction involves conjugate (Michael) addition of Stork enamine on β‐chloroalkylidene malonates and elimination of chloride ion. These Michael adducts were utilized as intermediates for the synthesis of highly substituted 1,4‐dialkyl‐2‐oxo‐6‐aryl/hetreoaryl‐1,2‐dihydro‐pyridine‐3‐carboxylic acid ethyl esters via 5 + 1 ring annulation protocol.     

Nano-Cuo–Au-catalyzed solvent-free synthesis of α-aminophosphonates and evaluation of their antioxidant and α-glucosidase enzyme inhibition activities

A new green and efficient method has been developed for the synthesis of α-aminophosphonates through one-pot three-component Kabachnik–Fields reaction. It involves the reaction of a 2-aminophenol with different substituted aromatic aldehydes and dimethyl phosphite in the presence of nanocopper oxide–gold (CuO–Au) catalyst under solvent-free conditions at 60?°C. Nano-CuO–Au catalyst was found to have many advantages like high activity, simple workup, and good (87%) to very high yields (96%). The products were characterized by IR, ¹H, ¹³C, and ³¹P NMR spectra and elemental analysis. All the synthesized compounds were screened for in vitro antioxidant and α-glucosidase inhibition activities. The compound 4b showed higher 2,2-diphenyl-1-picrylhydrazyl and H₂O₂ radical scavenging activity and compound 4e showed higher NO radical scavenging activity than the standard ascorbic acid. The compound 4j has much higher α-glucosidase enzyme inhibition activity than the standard acarbose.     

Synthesis and Antimicrobial Activity of Diethyl [(Substituted Phenyl)(5-hydroxy-3-methyl-1-phenyl-1H-pyrazol-4-yl)methyl]phosphonates

Russian Journal of General Chemistry - A series of structurally diverse and biologically potent diethyl [(substituted phenyl)(5-hydroxy-3-methyl-1-phenyl-1H-pyrazol-4-yl)methyl]phosphonates has...