Methods for the synthesis of mono- and polynuclear NH-tetrazoles. (Review)

Data on methods for the synthesis of monocyclic and polynuclear NH-unsubstituted tetrazoles are reviewed.Dedicated to Prof. H. Elguero on the occasion of his 65th birthday.St. Petersburg State Technological Institute (Technical University), St. Petersburg 198013, Russia; Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 867–884, July, 2000.     

Methods for the Synthesis of Isogramines and Their Chemical Properties. (Review)

Published data on methods for the synthesis of indole derivatives (isogramines) containing a dimethylamino group at positions 1, 2 and also at various positions of the benzene ring in the indole bicycle and their chemical properties are reviewed.__________Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 483–504, April, 2005.     

Synthesis and characterization of sulfur-voided cubanes. Structural analogues for the MoFe(3)S(3) subunit in the nitrogenase cofactor.

A new class of Mo/Fe/S clusters with the MoFe(3)S(3) core has been synthesized in attempts to model the FeMo-cofactor in nitrogenase. These clusters are obtained in reactions of the (Cl(4)-cat)(2)Mo(2)Fe(6)S(8)(PR(3))(6) [R = Et (I), (n)Pr (II)] clusters with CO. The new clusters include those preliminarily reported: (Cl(4)-cat)MoFe(3)S(3)(PEt(3))(2)(CO)(6) (III), (Cl(4)-cat)(O)MoFe(3)S(3)(PEt(3))(3)(CO)(5) (IV), (Cl(4)-cat)(Pyr)MoFe(3)S(3)(PEt(3))(2)(CO)(6) (VI), and (Cl(4)-cat)(Pyr)MoFe(3)S(3)(P(n)Pr(3))(3)(CO)(4) (VIII). In addition the new (Cl(4)-cat)(O)MoFe(3)S(3)(P(n)Pr(3))(3)(CO)(5) cluster (IVa), the (Cl(4)-cat)(O)MoFe(3)S(3)(PEt(3))(2)(CO)(6)cluster (V), the (Cl(4)-cat)(O)MoFe(3)S(3)(P(n)Pr(3))(2)(CO)(6) cluster (Va), the (Cl(4)-cat)(Pyr)MoFe(3)S(3)(P(n)Pr(3))(2)(CO)(6) cluster (VIa), and the (Cl(4)-cat)(P(n)Pr(3))MoFe(3)S(3)(P(n)Pr(3))(2)(CO)(6) cluster (VII) also are reported. Clusters III-VIII have been structurally and spectroscopically characterized. EPR, zero-field (57)Fe-M?ssbauer spectroscopic characterizations, and magnetic susceptibility measurements have been used for a tentative assignment of the electronic and oxidation states of the MoFe(3)S(3) sulfur-voided cuboidal clusters. A structural comparison of the clusters with the MoFe(3)S(3) subunit of the FeMo-cofactor has led to the suggestion that the storage of reducing equivalents into M-M bonds, and their use in the reduction of substrates, may occur with the FeMo-cofactor, which also appears to have M-M bonding. On the basis of this argument, a possible N(2)-binding and reduction mechanism on the FeMoco-cofactor is proposed.     

Methods for the Synthesis of Hydrazinopyridines and Some of Their Characteristics. (Review)

Data on the synthesis of hydrazinopyridines, their properties, and their application in various fields over the last 30 years are reviewed.     

Methods for the Synthesis of Heteroaryl-substituted 1,4-Benzo- and 1,4-Naphthoquinones. (Review)

Methods for the synthesis of heteroaryl-substituted 1,4-benzo- and 1,4-naphthoquinones with a C-C bond between the heterocycle and quinone fragments are reviewed. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 803–833, June, 2005.     

E.p.r. evidence for the formation of the six-coordinate pentafluoronitridotechnetate(VI) anion in solution

The reaction of AsPh4[TcNX4] (X=Cl or Br) with naked F– in MeCN solution has been shown by e.p.r. spectroscopy to result in the facile substitution of the halo ligands by fluoride. Addition of six equivalents of NBu4F·3H2O has provided, for the first time, direct evidence for the formation of the six-coordinate [TcNF5]2– in solution. An e.p.r. study of ligand exchange of Cs2[TcNCl5] (4 × 10–2 – 5 × 10–4 mol dm–3) in 28.6 mol dm–3 aqueous HF has shown that the distribution of the five [TcNFnCl4–n]– (n = ;0–4) species is concentration dependent, with the formation of [TcNF4]– being favoured by dilution.     

(1)H and (13)C NMR assignments for five anthraquinones from the mangrove endophytic fungus Halorosellinia sp. (No. 1403)

We report the unambiguous assignments of the (1)H and (13)C NMR spectra of two new natural products, namely, 1,4,5,6,7,9-hexahydroxy-2-methoxy-7-methyl-5beta,9beta,8abeta, 6alpha,10aalpha-hexahydroanthracen-10 (10aH)-one (1) and 1,4,6-trihydroxy-2-methoxy-7-methylanthracene-9, 10-dione (2), together with three known anthraquinones. These compounds were all isolated from the marine endophytic fungus No. 1403 collected from the South China Sea. Compounds 3 and 4 were isolated from the marine fungus for the first time. The structures were elucidated by the spectroscopic methods 1D and 2D NMR including COSY, HMQC, HMBC and NOE, and HREIMS. In our cytotoxicity assays, compound 5 showed cytotoxicity toward KB and KBv-200 cells with IC(50) of 1.40 and 2.58 microg/ml, respectively. In addition, the plausible biogenic relationship of compounds 1, 2, 3 and 4 is discussed.     

Polyfuryl(aryl)alkanes and their derivatives. 11. Optimization of the conditions for the synthesis of 2-nitroaryldifurylmethanes and the nature of the side products

It was found that 2-nitroaryldifurylmethanes can be obtained with high yields as a result of the condensation of derivatives of 2-nitrobenzaldehyde and sylvane in dioxane in the presence of perchloric acid. The reaction of 6-nitroveratraldehyde and sylvane in benzene in the presence of trimethylsilyl chloride leads to the formation of the product from the condensation of the aryldifurylmethane with the initial aldehyde and also a derivative of fitful-2,1-benzisoxazole.For Communication 10, see [1]Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 168–174, February, 1996.     

Transmetallation of n-(trialkylstannyl)methylimines. A new method for the generation and cycloaddition of 2-azaallyl anions.

Transmetallation of imines 1 at −78° with RLi provided 2-azaallyl anions 2, which readily undergo cycloaddition with olefinic anionophiles, providing pyrrolidines. Of particular note is the generation of unstabilized 2-azaallyl anions for the first time (Table 1, entries 1–3).