A reliable synthesis of 1,1-dimethylpyrazolium 5-oxides

Reliable syntheses of compounds having the novel 1,1-dimethylpyrazolium 5-oxide ring system are reported. The method involves treating the dimethylhydrazone of a β-ketoester with a small amount of concentrated sulfuric acid or other catalyst and heating under reduced pressure for 1–24 hours. In this manner two new members of the series have been prepared and characterized.     

The synthesis of 5-azaindole derivatives via mesoionic oxazolium 5-oxides

A synthesis of 5-azaindole derivatives is described. This synthetic approach involves the preparation of an appropriately substituted pyrrole derivative by a 1,3-dipolar cycloaddition reaction of dimethyl acetylenedicarboxylate with a mesoionic oxazolium 5-oxide. The pyrrole intermediate contains a protected β-aminoethyl substituent, and subsequent removal of the phthalimido protecting group results in cyclization to yield the corresponding 5-azaindole. This approach has been used for both acyclic and cyclic amino acid precursors of the 1,3-dipole which is ultimately used in the sequence.     

Synthesis of pyridazine derivatives XXII. s-triazolo[4, 3-b]pyridazine 5-oxides

The synthesis of s-triazolo[4,3-b] pyridazine 5-oxides is reported. To our knowledge, they are the first example of N-oxides of heteroaromatic azoloazines with a bridgehead nitrogen. They are easily rearranged, in particular when irradiated with ultraviolet light, into 6-hydroxy-s-triazolo[4,3-b]pyridazines.     

Enantiomeric resolution and determination of the absolute configuration of dibenzophosphole 5-oxides

The resolution of asymmetrically substituted dibenzophospholes via chromatographic separation of their cyclopalladium derivatives is described for the first time. The absolute configuration of the phosphorus atom was determined by X-ray crystallographic analysis in one case. A general NMR criterion for the complete determination of the configuration of this group of products is proposed. The enantiomeric excess of the resolved compounds was determined by NMR Eu(III) chemical displacement experiments and by HPLC using a chiral stationary phase.     

Reactions of 2,4-disubstituted 5-nitro-1,2,3-triazole 1-oxides. 2. Oxidation of 2-substituted 4-amino(alkylamino)-5-nitro-1,2,3-triazole 1-oxides

The oxidation of substituted aminonitrotriazole oxides to the corresponding dinitro derivatives of triazole and azotriazole oxides has been studied. Communication 1, see ref. [1]. N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 117913 Moscow, Russia; e-mail: cheminst@mail.psu.ru. Institute of Chemical Physics at Chernogolovka, Russian Academy of Sciences, 124432 Chernogolovka, Russia. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1356–1362, October, 1999.     

Perfluorinatedα-oxides

Perfluorinated-oxides from perfluoropropene, perfluoroisobutene, and 8-hydroperfluorooctene are prepared by oxidizing the perfluoroolefins with alkaline hydrogen peroxide. It is shown that treatment with hydrogen halide acids, alcohols, and thiourea leads to scission of the C-O bond of the -oxides at the ß-carbon atom. The products are a-bromoperfluorocarboxylic acids, esters of-alkoxyperfluorocarboxylic acids, and 2-amino-4-oxo-5-perfluoroalkylthiazolines.     

New nitrogen-containingα-oxides

N-(2,3-Epoxypropyl)--pyrrolidone and N-(2,3-epoxypropyl)--suecinimide have been obtained for the first time. It has been shown that N-(2,3-epoxypropyl)--pyrrolidone readily reacts with ammonia and diethylamine to form the corresponding amino alcohols.     

Synthesis of Dinaphtho-dioxaphosphepin-4-oxides, Epoxides and Bisphosphonates

A few new seven-membered phosphorus heterocyclic compounds and bis-phosphonates (5a—5g, 5f’, 5g’, 9 and 10) were prepared by the reaction of 4-bromo dioxaphosphepin (2) with various Grignard reagents followed by their oxidation with H2O2. All the compounds were thoroughly characterized by elemental analysis, IR, 1H, 13C, 31P NMR and mass spectral data. Their antimicrobial activity was evaluated and some of them possess significant activity.     

Determination of 5-oxides of pharmaceutically important phenothiazines by means of differential pulse polarography

Summary For the quantitative analysis of the sulphoxides (5-oxides) of pharmaceutically important phenothiazines in microgram amounts a method is developed using differential pulse polarography (DPP). It is suitable for the determination of at least 0.1 ol of the compounds. Surfactants present in the solution interfere. In degradation studies of phenothiazines isolation of the 5-oxides is necessary before the determination, since most phenothiazines show surface activity. The isolation is carried out by TLC. Standard deviation is about 4%.

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Bestimmung von 5-Oxiden pharmazeutisch bedeutsamer Phenothiazine durch Differential-Puls-Polarographie

Zusammenfassung Für die quantitative Analyse von Mikrogrammengen der Sulfoxide (5-Oxide) von Phenothiazinen ist eine differential-puls-polarographische Methode entwickelt worden. Diese Methode eignet sich für die Bestimmung von mindestens 0,1 Mol der Verbindungen. Oberflächenaktive Substanzen stören. Da viele Phenothiazine oberflächenaktiv sind, ist es notwendig, zuvor eine Isolierung des Sulfoxids durchzuführen, wenn die Methode zur Untersuchung des Abbaus von Phenothiazinen eingesetzt wird. Hierfür wird die Dünnschicht-Chromatographie verwendet. Die Standardabweichung liegt im Bereich von 4%.

     

Conformational studies of 5-substituted 3-aryl-1,2,3-oxathiazolidine 2-oxides using 13C-NMR

The title compounds were prepared and their ¹³C-nmr spectra were examined. On the basis of the data for the magnitudes of the γ shifts and the δ effects, four isomeric conformations of the compounds were discussed.     

Lithiation-methylation of thiasilinane 1-oxides

Lithiation-methylation of 3,3-dimethyl-1λ⁴,3-thiasilinane 1-oxide and 4,4-dimethyl-1λ⁴,4-thiasilinane 1-oxide under the action of butyllithium or lithium diisopropylamide and methyl iodide was studied. In both cases, monomethylation proceeds selectively α to the sulfoxide group to form 2,3,3-trimethyl-1λ⁴,3-thiasilinane 1-oxide and 2,4,4-trimethyl-1λ⁴,4-thiasilinane 1-oxide, respectively. Subsequently, 2,3,3-trimethyl-1λ⁴,3-thiasilinane 1-oxide undergoes monomethylation into the same α position to give 2,2,3,3-tetramethyl-1λ⁴,3-thiasilinane 1-oxide, while 4,4-dimethyl-1λ⁴,4-thiasilinane 1-oxide is dimethylated into the neighboring α’ position to form two stereoisomers of 2,4,4,6-tetramethyl-1λ⁴,4-thiasilinane 1-oxide with axial-equatorial or equatorial-equatorial methyl groups in the 2 and 6 positions.     

Synthesis of 2-(p-Toluenesulfonamido)-4-phenyl-4, 5-dihydro-1H-1, 3, 4-diazaphosphole 4-oxides

Some novel unsaturated five-membered organophosphorus heterocyclic compounds, 2-(p-toluenesulfonamido)-4-phenyl-4, 5-dihydro-1H-1, 3, 4-diazaphosphole 4-oxides 8 have been synthesized by Mannich-type reaction of p-toluenesulfonylguanidine with phenyldichlorophosphine and ketones.     

Halogenation of pyridine 1-oxides

The chlorination and bromination of α-lithiopyridine 1-oxides has been studied. Only dihalogenated pyridine 1-oxides are formed. In the case of bromination dipyridyl derivatives are also formed, and, indeed, predominate. Chloromercuration of the lithiopyridine 1-oxides gave highly insoluble, unresolvable mixtures of pyridylmercury derivatives. These could be brominated readily to give mixtures of 2-bromo- and 2,6-dibromopyridine 1-oxides.     

1,4,2-二氮磷杂环戊-5-(硫)酮类化合物除草活性的构效关系研究

利用与自由能有关的取代基的物理化学参数,考察了1,4,2－二氮磷杂环戊－5－(硫)酮类化合物对除草活性的相关性.根据Hansch方程及多元回归分析,进行了结构与活性定量关系的研究,建立了较好的结构与活性相关式,预测出化合物的活性并得到实验证实.     

Synthesis of 5-alkoxy-3-amino-7-nitro-1,2,4-benzotriazine 1-oxides from 1,3,5-trinitrobenzene

1-Alkoxy-3,5-dinitrobenzenes were nitrated to give 1-alkoxy-2,3,5-trinitrobenzenes. The reaction of the latter with guanidine affordsN-(2-alkoxy-4,6-dinitrophenyl)guanidines, which undergo cyclization under the action of KOH to form 5-alkoxy-3-amino-7-nitro-1,2,4-benzotriazine 1-oxides. Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1650–1652, September, 2000.