Synthesis,X-ray and DFT Studies of 6-halo-3-(hydroxymethyl)cinnolin-4(1H)-ones

Chemistry of Heterocyclic Compounds - The Richter cyclization was used for the synthesis of 6-halo-3-(hydroxymethyl)cinnolin-4(1H)-ones. X-ray analysis revealed that these compounds exist as dimers...     

Conducting Materials Based on Thermally Expanded Graphite

The electrical conductivity of composites produced from thermally expanded graphite, isoprene rubber, and polyvinyl chloride plastisol was studied as influenced by the process conditions.     

Cascade Transformations of (2,2-Diaryl-3,3-dichloroaziridin-1-yl)acetates

Esters of (2,2-diaryl-3,3-dichloroaziridin-1-yl)acetic acid prepared from glycine derivatives under alkylation conditions afford esters of 2-[N-alkyl-N-(2,2-diaryl-1-cyanovinyl)amino]-3,3-diarylacrylic acid in 20-40% yield. The reaction resulting in these compounds proceeds through a cascade of 3-chloro-2-azadiene and ylide intermediates. 3-Chloro-2-azadienes originating from (2,2-diaryl-3,3-dichloroaziridin-1-yl)acetates react with primary and secondary amines at the carbon atom of imine group providing ketenimines which undergo ketenimine-nitrile rearrangement or fragmentation. The other bases (KOH, MeONa, DBU) effect dehydrochlorination of the mentioned 3-chloro-2-azadienes giving nitrile-ylides which are trapped by nucleophilic reagents. The 3-chloro-2-azadiene obtained from methyl (2,2-diaryl-3,3-dichloroaziridin-1-yl)acetate and DBU was relatively stable and was isolated as an individual compound. (2,2-diaryl-3,3-dichloroaziridin-1-yl)propionates behave as nonfunctionalized dichloroaziridines.     

Oxygen Reaction at Carbonaceous Materials with Different Structure in Electrolytes Based on Lithium Perchlorate and Aprotic Solvents

Russian Journal of Electrochemistry - The necessity of the studying of carbonaceous materials differing in their surface area and structure is called for by the fact that these materials are used...     

1,3-dipolar cycloaddition of fluorinated azomethine ylides at the C=N bond

Azomethine ylides generated by reaction of difluorocarbene with N-alkyl- and N-arylimines derived from benzaldehyde and benzophenone react with N-benzylidenebenzenesulfonamide in a regioselective fashion, yielding the corresponding imidazolidin-4-ones via 1,3-dipolar cycloaddition at the C=N bond. Ylides generated from benzaldehyde imines give rise to mixtures of stereoisomeric 2,5-diphenyl-1-(phenylsulfonyl)-imidazolidin-4-ones, the cis isomer prevailing.Translated from Zhurnal Organicheskoi Khimii, Vol. 40, No. 10, 2004, pp. 1542–1548.Original Russian Text Copyright © 2004 by Novikov, Khlebnikov, Egarmin, Kopf, Kostikov.     

New approach to the nonparametric determination of the internal rotation potential from electron diffraction data. Reinvestigation ofm-bromonitrobenzene

A numerical algorithm for the nonparametric determination of the internal rotation potential from electron diffraction data using Tikhonov's regularization method is described. The range of admissible values of the regularization parameter is estimated using Hamilton's statistical criterion. m-Bromonitrobenzene was reinvestigated using this approach. It was found that the form of the potential may be reliably established only in the region of the minimum corresponding to the planar conformation of the molecule. Fourier series approximation of the experimental values of the potential in the region of the minimum gives the rotation barrier of 4.6–5.4 kcal/mole. The following basic geometrical parameters have been obtained (r_a in Å, ∠_α in deg, the error equals triple standard deviation): r(C?C)_ave=1.399(3), r(C?N)=1.459(16), 1.459(16), r(N=O)=1.244(3), r(C?Br)=1.884(6), r(C?H)=1.099(20), ∠CC_NC=123.9(1.4), ∠C_NCCBr=116.8(1.5), ∠C_NCC=116.6(1.9), ∠CNO=118.8(0.8). The results are compared with the data for the related compounds.     

Lead Finder docking and virtual screening evaluation with Astex and DUD test sets

Lead Finder is a molecular docking software. Sampling uses an original implementation of the genetic algorithm that involves a number of additional optimization procedures. Lead Finder's scoring functions employ a set of semi-empiric molecular mechanics functionals that have been parameterized independently for docking, binding energy predictions and rank-ordering for virtual screening. Sampling and scoring both utilize a staged approach, moving from fast but less accurate algorithm versions to computationally more intensive but more accurate versions. Lead Finder includes tools for the preparation of full atom protein and ligand models. In this exercise, Lead Finder achieved 72.9% docking success rate on the Astex test set when the original author-prepared full atom models were used, and 74.1% success rate when the structures were prepared by Lead Finder. The major cause of docking failures were scoring errors resulting from the use of imperfect solvation models. In many cases, docking errors could be corrected by the proper protonation and the use of correct cyclic conformations of ligands. In virtual screening experiments on the DUD test set the early enrichment factor of several tens was achieved on average. However, the area under the ROC curve ("AUC ROC") ranged from 0.70 to 0.74 depending on the screening protocol used, and the separation from the null model was not perfect-0.12-0.15 units of AUC ROC. We assume that effective virtual screening in the whole range of enrichment curve and not just at the early enrichment stages requires more accurate solvation modeling and accounting for the protein backbone flexibility.