Copper-Catalyzed Alkynylation of -Generated Azoalkenes: An Umpolung Approach to Pyrazoles.

A straightforward umpolung approach to regioselectively N-protected polysubstituted pyrazoles starting from aromatic α-halohydrazones and terminal alkynes has been developed. In this process, azoalkenes generated from α-halohydrazones are involved in the Cu(I)-catalyzed Michael addition with alkynes to give α-alkynyl-substituted hydrazones that cyclize to give the target pyrazoles in 37-85% yield. The method employs readily available starting materials and features good functional group compatibility (nitro, sulfonyl, cyano, trimethylsilyl, and primary bromoalkyl groups, esters, and alcohols are tolerated) and scalability.

Michael addition of -nucleophiles to azoalkenes provides simple access to phosphine oxides bearing an alkylhydrazone moiety.

β-Hydrazonophosphine oxides are precursors of useful organophosphorus compounds, including phosphorylated -heterocycles, α-aminophosphonates, and vinylphosphonates. In this work, a general transition metal-free synthesis of β-hydrazonophosphine oxides was developed. The method relies on the Michael addition of phosphine oxides RP(O)H to reactive azoalkenes (1,2-diaza-1,3-butadienes), which are generated from α-halohydrazones and Hunig's base.

Nucleophilic Halogenation of Cyclic Nitronates: A General Access to 3-Halo-1,2-Oxazines.

In this article, comprehensive studies on the nucleophilic chlorination and bromination of readily available six-membered cyclic nitronates (1,2-oxazine--oxides) are reported. Under optimized conditions (POCl or (COBr) with Hünig's base), 3-halo-substituted 1,2-oxazines, which are difficult to access by other routes, were obtained in good to high yields. The latter were shown to be convenient precursors to other 3-substituted 1,2-oxazine derivatives using Lewis/Brønsted acid-assisted substitution of the halide atom for C-, S-, and N-nucleophiles.

Acylation of Nitronates: [3,3]-Sigmatropic Rearrangement of in Situ Generated N-Acyloxy, N-oxyenamines.

Acylation of nitronates affords α-acyloxyoxime derivatives via an umpolung functionalization of the α-position. This transformation involves generation of hitherto unknown N-acyloxy, N-oxyenamines and their fast [3,3]-sigmatropic rearrangement driven by the cleavage of the weak N-O bond. The reaction has a broad scope, and it is regioselective in the case of nitronates possessing nonsymmetrically substituted α-positions.

Construction of bis-, tris- and tetrahydrazones by addition of azoalkenes to amines and ammonia.

Exhaustive Michael-type alkylations of amines and ammonia with azoalkenes (generated from α-halohydrazones) were demonstrated as an efficient approach to poly(hydrazonomethyl)amines - a novel class of polynitrogen ligands. An intramolecular cyclotrimerization of C=N bonds in tris(hydrazonomethyl)amine to the respective 1,4,6,10-tetraazaadamantane derivative was demonstrated.

[Analysis of frequency-contrast characteristics of digital X-ray image detectors].

The effect of various computing procedures on the results of estimation of parameters used for MTF calculation is analyzed. Experimentally evaluated modulation transfer functions of some types of digital X-ray image detectors are presented.

[Experimental and computational evaluation of quality of digital X-ray imaging].

The results of the use of specialized software for experimental and computational evaluation of the characteristics of digital X-ray detectors are analyzed.

[Effect of the treatment of relapsing bronchitis in children with combined interferon preparations applicated by different methods].

The clinico-immunological effect and significance of the rectal and inhalation methods of the application of recombinant IFN-alpha2 with complex immunoglobulin preparation (CIP) in the treatment of relapsing bronchitis in children have been determined. The determination of the levels of interferon activity in buccal secretions and in venous blood permits the objective evaluation of the immune responsiveness of the body and the treatment effect. The immunocorrecting action of the combined immunobiological preparation (recombinant IFN-alpha2 and CIP) is manifested by an increased level of endogenic interferon and the stimulation of phagocytic activity.

[The results of the monitoring of characteristics of digital receivers for X-ray images by using enterprise (VNIIMT) reference standard 01-22-04].

Described are the results of testing of methods of the new 01-22-04 standard designed for monitoring the image-quality parameters of digital X-ray converter-receivers (made alongside with tests of digital X-ray diagnostic units ProScan-7000 and ProScan-2000).

[The pathogenetic role of the infection component in children with lymphadenopathy under modern conditions].

Apart from lymphadenopathy types observed in well-known diseases (oncology and hematology pathologies, systemic lesions of connective tissues, tuberculosis, brucellosis, infection mononucleosis, toxoplasmosis, AIDS and other specific processes), there is an extensive group of lymphadenopathy (up to 70% of all disease cases), whose cause cannot be diagnosed by using the routine examination schemes. This was reflected in the diagnosis of "lymphadenopathy of unverified etiology" according to the MKB-1 now in force. Investigations of the role (in etiopathogenesis) of unverified lymphadenopathy types as observed in children with the infection component as well as optimization of their diagnosis and treatment schemes are elucidated in the paper.

[Choice of electron equipment for x-ray diagnostic digital scanning system].

The paper deals with the choice of electron equipment for X-ray diagnostic devices with digital image processing which are intended for population-based mass prophylactic examinations of lung. Guidelines for the optimization of the package of electron devices for processing and storing of data and for obtaining hard copies of X-ray films.