Synthesis of novel pyrazolopyrrolopyrazines,potential analogs of sildenafil

Synthesis of novel pyrazolopyrrolopyrazines is herein described with the aim to reach new specific PDE‐5 inhibitors of potential clinical interest in male erectile dysfunction.     

A rapid and versatile synthesis of novel pyrimido[5,4-b]carbazoles

A one-pot synthesis of 2-dialkylamino-5,11-dimethyl-6H-pyrimido[5,4-b]carbazol-4(3H)-ones, as new ellipticine analogs, starting from aminocarbazole derivatives is reported. This method allowed us to prepare a library of potentially useful compounds in the pharmaceutical field.     

Synthesis of 5-arylthiazoles. Comparative study between Suzuki cross-coupling reaction and direct arylation

A facile synthetic route to the new thiazol-5-ylboronic acid pinacol ester was described herein. Its reactivity toward Suzuki cross-coupling reaction was studied to provide various 5-arylthiazoles. A comparative study between Suzuki cross-coupling reactions and palladium-catalyzed C5–H direct arylation on thiazole ring was achieved.     

Preparation of 2,3-Dihydro [1,5] Benzothiazepines and 2,3-Dihydro [1,5] Benzodiazepines

2,3-dihydro[1,5] benzothiazepines and diazepines can be prepared by condensation of o-aminothiophenol or o-phenylenediamines with a variety of 3-chlorothieno-or benzothienopropanones.     

New mass spectrometric approaches to structural analysis in mixtures

Structural analysis of minor components in mixtures is a vital requirement in the development of any pharmaceutical compound. Mass spectrometry is uniquely able to give this kind of information on the trace amounts of material present as minor impurities in a drug substance. In this study we show that a combination of mass spectrometric analysers with different characteristics is an even more powerful approach with a higher chance of establishing a potential structure. In particular the advent of analysers capable of accurate mass measurement on small amounts of material has enabled structures to be proposed in situations where previously no real conclusions could be made. Copyright 1999 John Wiley & Sons, Ltd.     

Rational matrix approximation with a priori error bounds for non-symmetric matrix Riccati equations with analytic coefficients

In this paper the exact solution of the non-symmetric matrixRiccati equation with analytic coefficients is approximatedby a rational matrix function with a prefixed accuracy. Thisrational matrix function is locally defined as the exact solutionof a Riccati problem with matrix polynomial coefficients obtainedby truncation of the Taylor expansions of the matrix coefficientsof the original problem.     

A facile synthesis of new β-lactams

Several new β-lactams have been synthesized in good yields, via the cyclization of 3-chloro-N-arylpropionamides in a mixture of N, N-dimethylformamide and anhydrous sodium carbonate under a nitrogen atmosphere.     

Theoretical and experimental studies on spin-orbit coupling in caffeine

We compute the radiative phosphorescence lifetime of caffeine using CNDO/S wavefunctions. The importance of nπ*, πσ* and σπ* singlet and triplet states is considered. The calculated values are in good agreement with experimental determinations. The role played by two-electron terms is briefly discussed.     

Effect of Quinoline on Hydrodesulfurization and Hydrogenation on Bi- and Trimetallic NiMo(W)/Al2O3 Hydrotreating Catalysts

Russian Journal of Applied Chemistry - The effect of quinoline on the hydrodesulfurization and hydrogenation activities of bi- and trimetallic NiMo(W)/Al2O3 hydrotreating catalysts obtained using...