Uses of 2‐diazo‐4,5,6,7‐tetrahydrobenzo[b]thiophene derivatives in the synthesis of azoles,azines, and their fused derivatives

The reactions of 2‐diazo‐4,5,6,7‐tetrahydrobenzo[b]thiophene derivatives with dimeric adducts 2a and 2b gave the hydrazone derivatives 3a and 3b , respectively. The reactivity of the latter products towards various chemical reagents was studied in order to provide azole and azine derivatives incorporating the thiophene ring, and most of them showed high antimicrobial activity. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:108–115, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/hc.10003     

Resonance-enhanced multiphoton ionisation photoelectron spectroscopy of the ClO radical: the C 2 sigma- state

A (2 + 1) one-colour resonance-enhanced multiphoton ionisation study is carried out on the C 2 sigma- state of the ClO radical in the one-photon energy range 29,500-31,250 cm-1. The ClO radical is produced by one-photon photolysis of ClO2 employing 359.2 nm photons derived from a separate laser. In this way a significant concentration of vibrationally excited ClO in its spin-orbit split X 2 pi omega (omega = 3/2 or 1/2) electronic ground state is produced. In addition to mass-resolved excitation spectra, kinetic-energy resolved photoelectron spectra for the X 3 sigma-(v+)<--C 2 sigma-(v' = 3-5) transitions are measured. These transitions are not completely Frank-Condon diagonal, and indicate a decrease in bond length on removal of the Rydberg electron from the C 2 sigma- state. In addition to an unambiguous assignment of the C 2 sigma- state, valuable information is obtained on the degree of vibrational excitation with which the nascent ClO radical is formed in the photolysis of ClO2. Analysis of the photoelectron spectra is supported by Franck-Condon calculations based on potential energy curves either from experimental spectroscopic parameters, or obtained by theoretical ab initio methods.     

Infra-red study on the oxidation of cotton cellulose,viscose rayon and their hydrolysis residues

The i.r. absorption band at 5·8 μm, characteristic of the CO group resulting from the oxidation of cellulosic fibres, has been used to study the effect of acid hydrolysis on the accessible OH groups of cotton cellulose and viscose rayon. The results obtained in this investigation, and those previously found by measurement of the rate constant of oxidation, show that both the i.r. and the rate constant of oxidation may be used as quantitative measures of the accessible OH groups in the various cellulosic fibres. The effect of temperature on the rate constant of oxidation of some hydrolysis residues was studied. The activation energies of oxidation of the late cotton hydrocellulose and viscose hydrocellulose residues have been found to be 12·2 and 13·3 kcal. respectively.     

Reaction of 4-Aryl-3-thiosemicarbazides with Phenylisothiocyanate: A Facile Synthesis of Thiazole,Pyrazole and Pyrimidine Derivatives

The reaction of 4-aryl-3-thiosemicarbazides 1a-d with phenylisothiocyanate gave the intermediate potasium salts 2a-d . The latter afforded 3a-d, 13a-d and 19 upon the reaction with phenacyl bromide, monochloroacetic acid and ethyl bromocyanoacetate respectively.     

Photoelastic determination of stresses in multiple-pin connectors

The design, fabrication, and testing of photoelastic models of double-lap, multiple-pin connectors are discussed. Interest is in the stresses in the inner laps. These stresses are determined by constructing models with photoelastic inner laps and transparent-acrylic outer laps. The connectors have two pins, in tandem, parallel to the load direction. A photoelastic-isotropic point is shown to permit the evaluation of load sharing between the two pins. A numerical scheme, utilizing the isochromatic- and isoclinic-photoelastic data and a finite-difference representation of the planestress equilibrium equations, is used to compute the stresses around the two pins. Representative stress distributions and stress-concentration factors are shown.     

Phage display-derived inhibitor of the essential cell wall biosynthesis enzyme MurF

Background  

To develop antibacterial agents having novel modes of action against bacterial cell wall biosynthesis, we targeted the essential MurF enzyme of the antibiotic resistant pathogen Pseudomonas aeruginosa. MurF catalyzes the formation of a peptide bond between D-Alanyl-D-Alanine (D-Ala-D-Ala) and the cell wall precursor uridine 5'-diphosphoryl N-acetylmuramoyl-L-alanyl-D-glutamyl-meso-diaminopimelic acid (UDP-MurNAc-Ala-Glu-meso-A2pm) with the concomitant hydrolysis of ATP to ADP and inorganic phosphate, yielding UDP-N-acetylmuramyl-pentapeptide. As MurF acts on a dipeptide, we exploited a phage display approach to identify peptide ligands having high binding affinities for the enzyme.     

Novel synthesis of hydrazide-hydrazone derivatives and their utilization in the synthesis of coumarin, pyridine, thiazole and thiophene derivatives with antitumor activity

The reaction of cyanoacetyl hydrazine (1) with 3-acetylpyridine (2) gave the hydrazide-hydrazone derivative 3. The latter compound undergoes a series of heterocyclization reactions to give new heterocyclic compounds. The antitumor evaluation of the newly synthesized products against three cancer cell lines, namely breast adenocarcinoma (MCF-7), non-small cell lung cancer (NCI-H460) and CNS cancer (SF-268) was performed. Most of the synthesized compounds showed high inhibitory effects.     

Fracture of thick laminated composites

The fracture of thick laminated graphite/epoxy composites has been the subject of an extensive research program. The program was divided into three major areas of investigation which included laminate thickness, laminate stacking sequence, and part-through surface flaws. The results from this program are reviewed with emphasis placed on their applicability to the design of thick laminated composite structures. Paper was presented at 1985 SEM Spring Conference on Experimental Mechanics held in Las Vegas on June 9–14, 1985.     

Studies with 2‐arylhydrazononitriles: A novel simple,efficient route to 5‐acyl‐2‐substituted‐1,2,3‐triazol‐4‐amines

Efficient route to 5‐acyl‐2‐substituted‐1,2,3‐triazol‐4‐amines via reaction of 3‐oxo‐2‐(arylhydrazono)‐pentanenitrile with hydroxylamine hydrochloride is reported. X‐ray crystal structure has been made to confirm the structure of reaction products.