An expeditious one‐pot synthesis of substituted phenylazetidin‐2‐ones in the presence of zeolite

In this study, one‐pot rapid and efficient series of phenylazetidin‐2‐ones were synthesized from N,N‐dimethylaminobenzaldehyde, different substituted aromatic amines and phenylacetyl chloride in the presence of zeolite catalyst under microwave irradiation. We also reported schiff bases (1a–j) by classical and conventional microwave technique. The titled compounds are evaluated for their antimicrobial properties. The activities are due to C?O, C? N, linkages in 2‐azetidinones. All the compounds have shown comparable antibacterial activities. J. Heterocyclic Chem., (2011).     

Design,synthesis and screening of some novel benzoxazole based 1,3,4-oxadiazoles as potential antimicrobial agents

A series of novel 2-(5-substituted-[1,3,4]oxadiazol-2-yl)-benzoxazoles (7a–h) were synthesized in good yields in two different directions by involving benzoxazole-2-carboxylic acid (1) as raw material and benzoxazole-2-carbonyl chloride (2), benzoxazole-2-carboxylic acid methyl ester (3), benzoxazole-2-carboxylic acid hydrazide (4), benzoxazole-2-carboxylic acid N′-acetyl hydrazide (5a–d) and benzoxazole-2-carboxylic acid-ethylidene-hydrazides (6a–d) as reactive intermediates. The chemical structures of all the synthesized compounds were elucidated by their IR, ¹H NMR and ¹³C NMR and mass spectral data. Further, the target compounds were screened for their antimicrobial activity against various Gram-positive and Gram-negative bacteria.     

Antimony Trioxide as an Efficient Lewis Acid Catalyst for the Synthesis of 5-Substituted 1H-Tetrazoles

Sb₂O₃ was found to be effective as a catalyst for a smooth (2 + 3) cycloaddition of sodium azide with nitriles to afford 5-substituted 1H-tetrazoles in good yields.     

Ultrasound‐Assisted One‐pot Synthesis of Bis‐azetidinones in the Presence of Zeolite

Sonochemical method is an innovative task for the sustainable chemical research industry. In this work, an attempt was made to synthesize bis‐azetidin‐2‐ones ( 2a , 2b , 2c , 2d , 2e , 2f , 2g , 2h , 2i , 2j ) by Staudinger reaction ([2 + 2] ketene‐imine cycloaddition reaction) in the presence of zeolite by using both conventional and under ultrasound irradiation. The synthesized compounds have been elucidated on the basis of their elemental analysis and spectral data (IR, ¹H NMR, ¹³C NMR, and mass spectra) to evaluate its performance obtained under ultrasonic waves. It was observed that complete conversion to azetidin‐2‐ones occurred in 1–2 h by sonochemical method and in 15–46 h by conventional method. Finally, it has been observed that 2‐azetidinones synthesis using sonochemical method is an energy efficient and environmentally friendly technique over the conventional method.     

Molecular complexes of phenols with DDQ

Molecular complexes of phenols with DDQ have been studied spectrophotometrically in the temperature range of 10–30‡C in a solvent (CHC1₃) of low polarity under low donor concentrations. All the complexes exhibit one CT band each in the wavelength region where acceptor and donor do not have any absorption. The complexes are inferred to be of the π2π type and have R_y configuration in which the donor molecular orbital encompasses the substituent. The ionization potentials of the donors, the stability constants and thermodynamic parameters of the complexes have been evaluated.     

Concentration dependence of the spectroscopic and photochemical properties of atomic and molecular oxygen in argon matrices

Vacuum ultraviolet (VUV) excitation (200-100 nm) and visible emission (300-650 nm) spectra of O2 imbedded in Ar matrices at different concentrations are presented. At 0.1 and 0.2% concentrations a linear increase in the intensities of the excitation and emission spectra is observed. At these concentrations, photolysis of O2 is found to be negligible. At higher concentrations (0.5, 1 and 2%) the normalized intensities of the excitation and emission spectra of O2 decrease. With increasing concentration of O2 the permanent photolysis of O2 increases, which does not correlate, based on the excitation spectra of O in Ar, to the production of isolated O atoms. It has been shown that this anomalous behavior should be due to the formation of van der Waals dimers and oligomers at higher concentrations of O2 that upon photolysis produce ozone.     

Self-assembly of heteroleptic [2 x 2] and [2 x 3] nanogrids

Using the HETPHEN concept a general and quantitative approach to the formation of heteroleptic nanogrids is illustrated.