Regioselective synthesis of 6-aryl-5-(chloroethyl)salicylates by domino ‘[3+3] cyclization/homo-Michael’ reactions of 1,3-bis(silyloxy)-1,3-butadienes with 1-formyl- and 1-acetyl-1-aroyl-cyclopropanes

Functionalized 3-aryl-4-(chloroethyl)phenols are regioselectively prepared by domino ‘[3+3] cyclization/homo-Michael’ reactions of 1,3-bis(silyloxy)-1,3-butadienes with 1-formyl- and 1-acetyl-1-aroyl-cyclopropanes.     

Synthesis,Crystal Structure,and Antibacterial Activity of 1,2,4‐Triazoles and 1,2,4‐Triazol‐3‐one

A straightforward method has been developed for the synthesis of 1,2,4‐triazol‐3‐one 3 and 1,2,4‐triazoles 6a , 6b , 6c , 6d starting from N¹‐substituted‐N¹‐tosylhydrazonates 2 and hydrazine monohydrate. This methodology affords a number of 1,2,4‐triazol‐3‐one 3 and 1,2,4‐triazoles 6a , 6b , 6c , 6d in reasonable yields. The structures of all new compounds were elucidated using infrared, ¹H and ¹³C NMR, high‐resolution mass spectrometry, elemental analysis, and the X‐ray crystallography (for compounds 3 and 6a ). Some of the newly synthesized compounds were screened for their antibacterial activity.     

Neue Methode zur quantitativen Analyse von AES-Spektren

Summary The quantitative analysis of Auger electron spectra may lead to problems using Auger peak-to-peak heights (APPH), especially in connection with chemical peak deformation and peak overlap. To eliminate these problems a method has been developed and was applied to metalnonmetal compounds. An integral spectrum is fitted with reference spectra and correction spectra, background differences are compensated. To deal with chemical effects a digital filter process is used. In order to test this method a copper-palladium alloy series has been measured and evaluated according to this method. The results show that a more accurate quantification could be obtained than by using APPHs and sensitivity factors. As a further advantage, relative sensitivity factors are no longer necessary due to peak/background standardization.     

An efficient synthesis of 1,6- and 1,7-dibromo-3-aminoisoquinolines: versatile templates for the preparation of functionalized isoquinolines

An efficient synthetic route to 1,6- and 1,7-dibromo-3-aminoisoquinoline was devised. These intermediates served as ideal templates for the preparation of 3-aminoisoquinoline analogues functionalized at C(6) or C(7).     

New synthetic protocols for the preparation of unsymmetrical bisindoles

Novel unsymmetrical bisindoles were synthesized by a solvent-free C-C bond-formation reaction under mild conditions. Starting from aziridines or hydroxyl precursors, indoles have been used as C-nucleophiles to form new pharmacologically interesting bisindoles via an electrophilic aromatic substitution pathway in good to excellent yields. [reaction: see text]     

Experimental and quantum chemical study on the IR, UV and electrode potential of 6-(2,3-dihydro-1,3-dioxo-2-phenyl-1H-inden-2-yl)-2,3-dihydroxybenzaldehyde

Electrode potential of 6-(2,3-dihydro-1,3-dioxo-2-phenyl-1H-inden-2-yl)-2,3-dihydroxybenzaldehyde (DPDB) in methanol have been calculated theoretically. For the achievement of this task, the density functional theory (B3LYP/6-31G(d)) was employed with the inclusion of the entropic and thermochemical corrections to yield the free energies of the redox reactions. The electrode potential was also obtained experimentally by means of an electrochemical technique (cyclic voltammetry). The geometric parameters, the vibrational frequency values and the UV spectrum of DPDB and 2-(2,3-dihydro-1,3-dioxo-2-phenyl-1H-inden-2-yl)-5,6-dioxocyclohexa-1,3-dienecarbaldehyde (DPDD is the oxidized form of DPDB), were computed using the same methods. The calculated IR spectrum of DPDB, used for the assignment of the IR frequencies, was observed in the experimental FT-IR spectrum. The correlation between the theoretical and experimental DPDB vibrational frequencies was 0.996. This agreement mutually verified the accuracy of the experimental method and the validity of the applied mathematical model.     

Molecular parameterization and determination of the electrode potentials of anticoagulant derivatives: Electrochemical and quantum chemical study

This research presents calculations and computation of two anticoagulant derivatives electrode potentials in methanol. For this purpose, the ab initio molecular orbital calculations (HF) and density functional theory (DFT) together with the 6-31G(d) basis set were utilized. The calculated values were compared with the experimental values obtained by linear sweep voltammetry. The observed and the calculated changes in the reduction potential of the anticoagulant derivatives differed from those of the reference compound (catechol), being less than 20 mV. In this way, a method was provided, by which the reduction potentials of the related molecules could be predicted very accurately. Actually, the resulting data illustrated that the method was likely to be useful for the prediction of biomolecules electrode potentials in different aprotic solvents. The bond lengths, bond angles and dipole moment of the studied compounds were calculated in two different solvents and the solvent effects were discussed.     

Effect of Surface Corrugation on Convection in a Three-Dimensional Finite Box of Fluid Saturated Porous Material

The problem of finite amplitude thermal convection in a three-dimensional finite box of fluid saturated porous material is investigated, when the lower boundary of the fluid is corrugated. The nonlinear problem of three-dimensional convection in the box for the values of the Rayleigh number close to the classical critical value and for small values of the amplitude of the corrugations is solved by a perturbation technique. The preferred mode of convection is determined by stability analysis. In the absence of corrugation three-dimensional modes of convection can be either stable or unstable depending on the values of the aspect ratios of the box, while two-dimensional rolls are always stable, provided that the box aspect ratios allow the existence of such modes of convection. In the presence of boundary corrugation with the appropriate form, different three-dimensional or two-dimensional modes of corrugation can be stable or unstable. For a rough boundary with local roughness sites, the location, size, and number of the roughness elements plus the wave numbers of the convection modes and the box aspect ratios can all play a role leading to either stable or unstable particular three- or two-dimensional flow patterns. For a wavy boundary, resonant wave-vector excitation can lead to the preference of stable two- or three-dimensional flow patterns whose wave vectors are in a subset of those due to the wavy boundary, while nonresonant wave-vector excitation can lead to the preference of stable flow patterns whose wave vectors are not generally in a subset of those due to the wavy boundary. Heat transported by convection can either be enhanced or be reduced by certain proper forms of the corrugations and by appropriate values of the box aspect ratios. Due to the surface corrugation highly subcritical modes of convection are stable, while highly supercritical modes of convection are unstable. Received 24 July 1998 and accepted 11 April 1999     

First synthesis of 4-(arylsulfonyl)phenols by regioselective [3+3] cyclocondensations of 1,3-bis(silyloxy)-1,3-butadienes with 2-arylsulfonyl-3-ethoxy-2-en-1-ones

The formal [3+3] cyclization of 1,3-bis(silyloxy)-1,3-butadienes with readily available 2-arylsulfonyl-3-ethoxy-2-en-1-ones resulted in regioselective formation of 4-(arylsulfonyl)phenols.