There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

The freely accessible web resource PASS Online is presented. This resource is designed for the prediction of the biological activity spectra of organic compounds based on their structural formulas for more than 4000 types of biological activity with average accuracy above 95% (
 http://www.way2drug.com/passonline
 ). The prediction is based on an analysis of the structure-activity relationships in the training set containing information on the structure and biological activity of more than 300000 organic compounds. The possibilities and limitations of this approach are described. Recommendations are given for interpreting the prediction results. Examples are given for the practical use of the PASS Online web resource in order to establish priorities for chemical synthesis and biological testing of substances on the basis of prediction results. The further trends are considered for the using PASS Online as an Internet platform for joint projects of academic researchers for the search and development of new pharmaceutical agents.

https://link.springer.com/content/pdf/10.1007%2Fs10593-014-1496-1.pdf

Prediction of the Biological Activity Spectra of Organic Compounds Using the Pass Online Web Resource

Advanced Organic Chemistry: Reactions, Mechanisms And Structure

The preparation of N-methylpyrazoles is usually accomplished through reaction of a suitable 1,3-diketone with methylhydrazine in ethanol as the solvent. This strategy, however, leads to the formation of regioisomeric mixtures of N-methylpyrazoles, which sometimes are difficult to separate. We have determined that the use of fluorinated alcohols such as 2,2,2-trifluoroethanol (TFE) and 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) as solvents dramatically increases the regioselectivity in the pyrazole formation, and we have used this modification in a straightforward synthesis of fluorinated analogs of Tebufenpyrad with acaricide activity.

Improved regioselectivity in pyrazole formation through the use of fluorinated alcohols as solvents: synthesis and biological activity of fluorinated tebufenpyrad analogs.

Despite prior reports of several really effective catalytic and non-catalytic approaches towards Biginelli’s 3,4-dihydropyrimidin-2(1H)-ones, an overwhelming number of new catalysts for the Biginelli reaction have been recently published. Most of the catalysts are somewhat exotic, expensive, harmful and even uneffective in the absence of acidic additives. Herein we reduce the “yet-another-one-catalyst” idea to absurdity by proposing NaCl promotes the reaction that actually requires no catalyst, neither rare nor expensive.

A chemical placebo: NaCl as an effective, cheapest, non-acidic and greener catalyst for Biginelli-type 3,4-dihydropyrimidin-2(1H)-ones (-thiones) synthesis.

The data on the synthesis, structure and chemical transformations of 2-(het)arylhydrazono-1,3-dicarbonyl compounds is surveyed. The synthetic potential and possible applications of the title compounds are analyzed.

https://iopscience.iop.org/article/10.1070/RC2010v079n01ABEH004048/pdf

2-(Het)arylhydrazono-1,3-dicarbonyl compounds in organic synthesis

Synthesis and the reactions of trifluoromethylated 1,2,3-triketones 2-(het)arylhydrazones and 4,7-dihydroazolo[5,1-c]triazines

1,2,3-Triketone 2-(antipyrin-4-yl)hydrazones were synthesized via the azo-coupling reactions of 1,3-diketones with 2-(antipyrin-4-yl)diazonium chloride The fluoroalkyl-containing hetarylhydrazone enters into cyclocondensation with hydrazines at the 1,3-dicarbonyl fragment to yield 3-tetrafluoroethyl derivatives of pyrazole It was found that 1,2,3-triketone 2-(antipyrin-4-yl)hydrazones and N-(2-hydroxyethyl)-substituted pyrazole exhibit analgesic activity comparable with that of their structural analog analgin (metamizole sodium), but do not possess antipyretic properties In contrast, N-phenyl-substituted pyrazole did not exhibit analgesic properties but produced a certain antipyretic effect four hours after pyrogenic administration Fluoroalkyl-containing compounds are less toxic substances than nonfluorinated 2-(antipyrin-4-yl)hydrazone and analgin

Synthesis, analgesic and antipyretic activity of 2-(antipyrin-4-yl)hydrazones of 1,2,3-triketones and their derivatives

Fluoroalkyl-containing 1,2,3-triketone 2-(2,3-dimethyl-5-oxo-1-phenyl-1,2-dihydropyrazol-4-yl)-, 2-(4-ethoxycarbonylpyrazol-3-yl)-, and 2-(1,2,4-triazol-3-yl)hydrazones were synthesized by the azo coupling reactions of fluorinated 1,3-diketones with the corresponding hetaryldiazonium chlorides. The hetarylhydrazones thus synthesized were subjected to cyclocondensation with hydrazines at the 1,3-dicarbonyl fragment to give 3-fluoroalkyl-4-hetarylazopyrazoles.

Synthesis of fluoroalkyl-containing 1,2,3-triketone 2-hetarylhydrazones and their reactions with hydrazines

A convenient procedure has been developed for the synthesis of fluoroalkyl-substituted 6-aryl-4-hydroxy-2-oxo-(thioxo)hexahydropyrimidine derivatives by three-component condensation of fluorinated β-dicarbonyl compounds with aromatic aldehydes and urea or thiourea in the absence of a solvent using 6 mol % of 1-butyl-3-methylimidazolium tetrafluoroborate as catalyst.

One-step solvent-free synthesis of fluoroalkyl-substituted 4-hydroxy-2-oxo(thioxo)hexahydropyrimidines in the presence of 1-butyl-3-methylimidazolium tetrafluoroborate

Olga G. Khudina

Papers

2-(Het)arylhydrazono-1,3-dicarbonyl compounds in organic synthesis

Synthesis and the reactions of trifluoromethylated 1,2,3-triketones 2-(het)arylhydrazones and 4,7-dihydroazolo[5,1-c]triazines

Synthesis, analgesic and antipyretic activity of 2-(antipyrin-4-yl)hydrazones of 1,2,3-triketones and their derivatives

Synthesis of fluoroalkyl-containing 1,2,3-triketone 2-hetarylhydrazones and their reactions with hydrazines

One-step solvent-free synthesis of fluoroalkyl-substituted 4-hydroxy-2-oxo(thioxo)hexahydropyrimidines in the presence of 1-butyl-3-methylimidazolium tetrafluoroborate