Remarkable selectivity in the reaction of l-trityl-2-lithioimidazoles with t-butyl halogenoacetates

2-Lithio-1-triphenylmethylimidazoles react with t-butyl halogenoacetates to give a variety of products, the nature of which is cleanly determined by the halogen atom. With chloroacetate the products are chloromethyl ketones, while bromacetate gives di-t-butyl imidazolesuccinates, and iodoacetate yields iodoimidazoles. In each case 50% of the parent triphenylmethylimidazole is recovered from the reaction. When the triphenylmethyl substituent is replaced by the N,N-dimethylsulfamoyl group, reaction with bro-moacetate is suppressed, but t-butyl chloroacetate and iodoacetate again give chloroketones and aryl iodides respectively.     

Facile Syntheses of (6S)-6-Fluoroshikimic Acid and (6R)-6-Hydroxyshikimic Acid

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Convenient and Scalable Process for the Preparation of Indole via Raney Nickel–Catalyzed Hydrogenation and Ring Closure

An efficient and practical method for the synthesis of indole as a key starting material for many useful chemicals is described. Using 2-nitrotoluene as starting material, hydroxymethylation with formaldehyde under alkaline conditions gave 2-(2-nitrophenyl)ethanol on a large scale. Raney Ni catalyst was used for both reduction of the nitro group as well as for the indole formation. The overall yield was 78% from 2-nitrotoluene.     

Surface‐enhanced Raman spectra of melamine and other chemicals using a 1550 nm (retina‐safe) laser

Many trace chemical analyses are being transitioned from the lab to the field, among which is surface‐enhanced Raman spectroscopy. Although initial portable Raman analyzers primarily employ 785 nm laser excitation, recent studies suggest longer wavelengths, with an appropriate surface‐enhanced Raman‐active substrate, may provide equal sensitivity. Furthermore, 1550 nm excitation may provide added safety for the user, in that permanent retina damage does not occur. Here, we show that a reasonable enhancement factor can be obtained for melamine using 1550 nm laser excitation that is nearly equivalent to those obtained using 785 and 1064 nm laser excitation. We also demonstrate that a number of other chemicals of interest can be measured by 1550 nm surface‐enhanced Raman scattering, albeit only modest sensitivity is achieved because of instrument limitations, not enhancement factors. Copyright © 2011 John Wiley & Sons, Ltd.     

Modification of the omega-meson lifetime in nuclear matter

Information on hadron properties in the nuclear medium has been derived from the photoproduction of omega mesons on the nuclei C, Ca, Nb, and Pb using the Crystal Barrel/TAPS detector at the ELSA tagged photon facility in Bonn. The dependence of the omega-meson cross section on the nuclear mass number has been compared with three different types of models: a Glauber analysis, a Boltzmann-Uehling-Uhlenbeck analysis of the Giessen theory group, and a calculation by the Valencia theory group. In all three cases, the inelastic omega width is found to be 130-150 MeV/c(2) at normal nuclear matter density for an average 3-momentum of 1.1 GeV/c. In the rest frame of the omega meson, this inelastic omega width corresponds to a reduction of the omega lifetime by a factor approximately 30. For the first time, the momentum dependent omegaN cross section has been extracted from the experiment and is in the range of 70 mb.     

Surface-enhanced Raman spectral measurements of 5-fluorouracil in saliva

The ability of surface-enhanced Raman spectroscopy (SERS) to measure 5-fluorouracil (5-FU) in saliva is presented. The approach is based on the capacity of Raman spectroscopy to provide a unique spectral signature for virtually every chemical, and the ability of SERS to provide microg/mL sensitivity. A simple sampling method, that employed 1-mm glass capillaries filled with silver-doped sol-gels, was developed to isolate 5-FU from potential interfering chemical components of saliva and simultaneously provide SERSactivity. The method involved treating a 1 mL saliva sample with 1 mL of acetic acid, drawing 10 microL of sample into a SERS-active capillary by syringe, and then measuring the SER spectrum. Quality SER spectra were obtained for samples containing as little as 2 microg of 5-FU in 1 mL saliva. The entire process, the acid pretreatment, extraction and spectral measurement, took less than 5 minutes. The SERS of 5-fluorouridine and 5-fluoro-2'-deoxyuridine, two major metabolites of 5-FU, were also measured and shown to have unique spectral peaks. These measurements suggest that disposable SERS-active capillaries could be used to measure 5-FU and metabolite concentrations in chemotherapy patient saliva, thereby providing metabolic data that would allow regulating dosage. Tentative vibrational mode assignments for 5-FU and its metabolites are also given.     

Proton-deuteron elastic scattering at 135 MeV with BINA

Differential cross sections and vector analyzing powers for the p + d → p + d reaction have been measured using a new experimental setup (BINA) at KVI. The data are compared with published results and are found to be significantly different.     

Syntheses of ethyl 3-deoxy-3,3-difluoro-d-arabino-heptulosonate and analogues

The difluorinated analogues of 3-deoxy-d-arabino-heptulosonic acid (DAH) 12, 24 and its enantiomer have been synthesised from d- and l-erythrose via a Reformatsky reaction which gave a mixture of diastereoiosmers in favour of the anti isomer.     

Energy Absorption Characteristics of a Novel Asymmetric and Rotatable Re-entrant Honeycomb Structure

Based on the symmetric re-entrant honeycomb(S-RH)structure with negative Poisson's ratios,a novel asymmetric and rotatable re-entrant honeycomb(AR-RH)structure ...