N. I. Vorozhtsov

Pharmacological Activity of 4,5-Dihydropyrazole Derivatives (Review)

The various types of pharmacological activity of 4,5-dihydropyrazole derivatives are reviewed. Attention is focused on the influence of various substituents in the dihydropyrazole core on the pharmacological effects of these compounds.

Synthesis 5-(pyrazolin-3-ylmethylidene)-2-thiohydantoins and 2-alkylsulfanyl-5-(pyrazolin-3-ylmethylidene)-3,5-dihydro-4 H -imidazol-4-ones

A reaction of 3-allyl- and 3-phenylthiohydantoins with 1,5-diphenyl- and 1-phenyl-substituted 3-formyl-2-pyrazolines was used to obtain a series of 5-(pyrazolin-3-ylmethylidene)-2-thioxotetrahydro-4H-imidazol-4-ones, the subsequent alkylation of which with methyl iodide or ethyl chloroacetate gave the corresponding 2-alkylthio-5-(pyrazolin-3-ylmethylidene)-3,5-dihydro-4H-imidazol-4-ones in the yields from 30 to 77%. The oxidation of (5Z)-3-phenyl-5-[(1,5-diphenylpyrazolin-3-yl)methylidene]-2-methylsulfanyl-4,5-dihydroimidazol-4-one with lead tetraacetate led to the corresponding pyrazole in 48% yield.

Acylation of 1-arylpyrazolidin-3-ones

Acylation of 1-arylpyrazolidin-3-ones using aromatic acid anhydrides and chlorides in the presence of base occurs principally at the oxygen atom to give 1-aryl-3-acyloxy-2-pyrazolines, subsequent heating or microwave irradiation of which leads to the corresponding N-acylpyrazolidin-3-ones. The action of aliphatic acid anhydrides and chlorides on 1-arylpyrazolidin-3-ones gives predominantly the N-acylpyrazolidin-3-ones.

Synthesis of 4,5-dihydro-1H-pyrazoles with chiral substituents at position 3 or 5

New chiral 4,5-dihydro-1H-pyrazole hydroxy and amino derivatives containing functional groups at β-position of the side chain were obtained by the selective oxidation of the corresponding pyrazolidine derivatives with air oxygen at low temperature without affection of the centers of chirality.

Copper(ii) complexes with 3-(2-pyridyl)-4,5-dihydro-1H-pyrazoles: synthesis, structural and electrochemical studies

Three new copper(ii) complexes with the 3-(2-pyridyl)-4,5-dihydro-1H-pyrazole ligands were obtained by reactions of appropriate organic ligands with CuCl2·2H2O. The structures of the complexes were determined by X-ray diffraction. The molecular formula of all the complexes can be written as 2(L·MCl2) (L is an organic ligand). The coordination polyhedron of either copper ion is a distorted trigonal bipyramid made up of two N atoms (coming from the pyrazoline and pyridine rings) and one axial and two bridging chloride anions. The electrochemical behavior of 1,5-diphenyl-3-(2-pyridyl)-4,5-dihydro-1H-pyrazole and its CuII complex was studied by cyclic voltammetry; the mechanisms of their electrooxidation and electroreduction were proposed.

1-Amino-3-(4-methoxybenzylamino)-1-phenylpropane as a new water-soluble fluorescent reagent to zinc ion

Zinc(II) plays an important role in biology and medi cine being involved in many physiological and pathological processes in the human organism.1 Rapt attention is given to search for fluorescent labels to Zn2+ ions, since the fluorescence analysis method2 makes it possible to rapidly and quantitatively determine the content of these ions. However, the value of many reagents related mainly to heterocyclic compounds2 decreases because their low sol ubility in water3 and the non stoichiometric amount of the reagent required for determination of Zn2+ ions. The num ber of known water soluble reagents is rather restricted.4 We studied the fluorescence properties of new water soluble linear diamine, viz., 1 amino 3 (4 methoxy benzylamino) 1 phenylpropane (L). Compound L was synthesized from the corresponding pyrazolidine deriva tive5 by the cleavage at the N—N bond with borane in THF using our earlier developed procedure.6 The fluores cence excitation spectrum of diamine ligand L in an aque ous medium contains a band with a maximum at 228 nm (Fig. 1, curve 1). The excitation of a solution of com pound L with a wavelength of 228 nm results in the ap pearance of a fluorescence band with a maximum at

Synthesis and spectral features of new 1-alkyl-5-(indol-2(3)-yl)pyrrolidin-2-ones

The mass spectrometric behavior of 1-alkyl-5-(1H-indol-2-yl)pyrrolidin-2-ones and 1-alkyl-5-(1H-indol-3-yl)pyrrolidin-2-ones was studied and the fragmentation of these compounds was established. The product of N-methylindole reaction with 1-benzyl-5-hydroxypyrrolidin-2-one was shown to be 1-benzyl-5-(1-methylindol-3-yl)pyrrolidin-2-one.