The reactions of 3-ethoxycarbonylmethylene-3,4-dihydroquinoxalin-2(1H)-one and its derivatives in the synthesis of benzodiazepines and benzimidazoles: reinvestigation,structural reassignment,and new insight

The reaction of 3-ethoxycarbonylmethylene-3,4-dihydroquinoxalin-2(1H)-one with the Vilsmeier reagent, the treatment of 3-(3,4-dihydroquinoxalin-2(1H)-on-3-yl)-1,2-dihydro-1,5-benzodiazepin-2(1H)-one hydrochloride with 10% sodium hydroxide and 3-benzimidazoylquinoxalin-2(1H)-one with both 1,2-phenylenediamine dihydrochloride, and the reactions of 1,2-phenylenediamine have been reinvestigated and the structures of these reaction products have been revised. It has been shown that in all the three cases other regioisomers of products have been formed as distinct from the literature data. The mechanisms to explain the formation of the products are suggested.     

Synthesis of pyrroloquinolines from substituted 6-aminoindoles and oxaloacetic ester

It was established that the initial condensation of substituted 6-aminoindoles and oxaloacetic ester in boiling benzene with the addition of catalytic amounts of acetic acid takes place exclusively through the carboxyl group of the keto ester with the formation of the corresponding enamines, which successfully undergo thermal cyclization (biphenyl, 280°C) to pyrroloquinolines. Here, irrespective of the nature of substituents at the N-1 and C-5 atoms enamines with a free position 7 are transformed into pyrrolo-[2,3-f]quinolines (structural analogs of vitamin PQQ) while 7-OMe-substituted enamines give pyrrolo[3,2-g]quinolines with linear fusion of the rings. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 991–1002, July, 2008.     

Estimation of the energetic nonhomogeneity of the surface of oxide and carbon materials

The molecular statistical method for evaluating the distribution of active sites of various adsorbents relative to their energies has been improved. This method is used not only for the treatment of experimental data on the adsorption of hydrocarbons on various adsorbents, which is the usual procedure, but also data on the adsorption of polar water and methanol molecules on the active sites of adsorbent surfaces. Two types of active sites differing in energy have been shown to exist on the surface of graphitized carbon black, the complex shungite carbon/mineral adsorbent, and modified Silochrom. Chromatographic, calorimetric, and structural adsorption data were used to establish the relationship between the observed maxima of the energy distribution function of the adsorption sites with concrete adsorption sites or pores of the surface, on which the molecules are adsorbed. Translated from Teoreticheskaya i éksperimental'naya Khimiya, Vol. 44, No. 5, pp. 315–320, September–October, 2008.     

Classification of compact lorentzian 2-orbifolds with noncompact full isometry groups

Among closed Lorentzian surfaces, only flat tori can admit noncompact full isometry groups. Moreover, for every n ≥ 3 the standard n-dimensional flat torus equipped with canonical metric has a noncompact full isometry Lie group. We show that this fails for n = 2 and classify the flat Lorentzian metrics on the torus with a noncompact full isometry Lie group. We also prove that every two-dimensional Lorentzian orbifold is very good. This implies the existence of a unique smooth compact 2-orbifold, called the pillow, admitting Lorentzian metrics with a noncompact full isometry group. We classify the metrics of this type and make some examples.     

Fused polycyclic nitrogen-containing heterocycles 21. Condensation of 4-hydroxy-3,5-diphenyl-2-phenyliminothiazolidine with 5-fluoro-4-morpholino- and 4-(4-methylpiperazino)-1,2-phenylenediamines

The condensation of 4-hydroxy-3,5-diphenyl-2-phenyliminothiazolidine with 5-fluoro-4-morpholino- and 5-fluoro-4-(4-methylpiperazino)-1,2-phenylenediamines leads to region-isomeric thiazolo[3,4-a]quinoxalines differing in substituents in positions 7 and 8 of the benzene ring. From the ratio of isomers formed it follows that the mesomeric effect of a fluorine atom in 1,2-phenylenediamines is comparable with the influence of an aminosubstituent.