A new approach for the solid-phase synthesis of pyrrolo[2,1-c][1,4]benzodiazepines involving reductive cleavage

A methodology based on reductive cleavage followed by cyclization, for the solid-phase synthesis of pyrrolo[2,1-c][1,4]benzodiazepines employing DIBAL-H, is described.     

First example of the C-alkylation of indoles with Baylis-Hillman acetates

Baylis-Hillman acetates undergo S_N2′ allylic substitution with indoles in the presence of 20 mol % of indium tribromide under mild conditions to afford a new class of substituted indoles in high yields with (E)-stereoselectivity. The stereochemistry of the products was assigned by various NMR experiments.     

New sphingolipids and a sterol from a lobophytum species of the Indian ocean

Chemical investigation of a soft coral species of the genus Lobophytum has resulted in the isolation of three new sphingolipids--(2S,3S,4R)-2-nonadecanoylamino-octadecane-1,3,4-triol (1), (2S,3R,4E,8E)-[(2'R)-2'-hydroxyheptadecanoylamino]-4,8-octadecadiene-1,3-diol (2), 1-O-(beta-D-glucopyranosyl)-(2S,3R,4E,8E)-2-[(2'R)-2'-hydroxynonadecanoylamino]-9-methyl-4,8-octadecadiene-1,3-diol (3) and a sterol--(24S)-ergost-5-en-3beta,7beta-diol (4) along with the known sphingolipid--(2S,3R,4E,8E)-2-hexadecanoylamino-4,8-octadecadien-1,3-diol (5) which showed cytotoxicity against human peripheral blood mononuclear cells (PBMC).     

Practical, efficient, stereoselective, formal synthesis of (2R,3R,4R)-3-hydroxy-4-methylproline

A highly efficient and stereoselective synthesis of (2R,3R,4R)-HMP is disclosed employing the sulfinyl group as an internal nucleophile to functionalize an olefin in the key step of the reaction sequence. The proline ring is elaborated by a (4C+N) cyclization.     

Estimation of chromium in ores and beneficiated products: an ultrasonic approach

Cr(III) slowly forms a violet complex with EDTA at pH 3.5 +/- 0.2 under normal conditions. The complex formation can be catalyzed by irradiating the reacting mixture with ultrasonic waves. Quantitative formation of the complex was possible with ultrasonic waves of 15 W/cm(2) intensity within 7.5 min of sonication. This method may be successfully applied to the determination of chromium in ores and beneficiated products containing 20-60% Cr(2)O(3) without separating the analyte from the matrix elements.     

Synthesis and human leukocyte elastase inhibitory activity of novel 2-spiro(2′,2′-diphenylcyclopropane) cephalosporin sulfones

A new series of 2-spiro(2,2-diphenylcyclopropane) cephalosporin sulfones was synthesizes as potent human leukocyte elastase inhibitors.SynPhar Laboratories Inc., #2 Taiho Alberta Centre, 4290-91A Street, Edmonton, Canada T6R 5V2. Published in Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1517–1523, November, 1998.     

Studies on monobactams II. Synthesis and β-lactamase inhibitory activity of 4α-methyl-3-[(thien-2-yl)-methylene]-2-azetidinone-1-sulfonate

Two monobactam derivatives, potassium 4-methyl-(3E)-[(thien-2-yl)methylene]-2-azetidinone-1-sulfonate and its (3Z)-isomer, were prepared and evaluated for their -lactamase inhibitory activities. These compounds were devoid of -lactamase inhibitory activity.SynPhar Laboratories Inc., #2, 4290-91A Street, Edmonton, Alberta T6E 5V2, Canada. Tokushima Research Institute, Taiho Pharmaceutical Co., Ltd., 224-2 Ebisuno Hiraishi, Kawauchi-cho, Tokushima 771-01, Japan. Published in Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1548–1552, November, 1998.     

Application of sodium metaperiodate for the determination of ribavirin in pharmaceutical formulations

Three simple and sensitive visible spectrophotometric methods (A-C) have been described for the assay of ribavirin either in pure form or in pharmaceutical formulations. They are based on the oxidation of ribavirin with excess sodium metaperiodate and estimating either the products formed (dialdehyde with MBTH, method A; iodate with metol-sulphanilamide, in the presence of Mo(VI) and iodide, method B) or the amount of periodate consumed (celestine blue in the presence of telurium (IV), method C). All of the variables have been optimized and the reaction mechanisms presented. The concentration measurements are reproducible within a R.S.D. of 1.0%. Recoveries are 99.2-101.2%.     

K α L 1 satellite multiplet structure of photon-excited chlorine atoms

Summary An attempt is made to study theK _α L ¹ satellite multiplet structure of chlorine atoms in different compounds by photon excitation. A comparison of the averageK _α L ¹ group energy shift from the diagram line with those based on Dirac-Fock evaluations with different number ofM-shell electrons shows a reasonable agreement. The intensity ratios are found to be higher than those studied in Mg compounds in general.