Die Reaktion von 4,6-Dinitroisophthalaldehyd und 4,6-Dinitroisophthalonitril mit Pyridin

The reaction of 4,6-dinitroisophthalaldehyde and 4,6-dinitroisophthalonitrile with pyridine 4, 6-Dinitroisophthalaldehyde ( 4 ) gives on reaction with pyridine 4,6-diformyl-3-(1′-pyridinio)-1-phenolate ( 5 ), whereas 4,6-dinitroisophthalonitrile ( 7 ) gives under the same conditions one main product: 3-(1′)-pyridinio-4, 6-dicyano-1-phenolate ( 10 ) and two side products: 2-(1′-pyridinio)-4, 6-dicyano-3-nitro-1-phenolate ( 11 ) and 4, 6-dicyano-3-nitro-1-phenol ( 12 ). The new structures were elucidated by ¹H-NMR. and ¹³C-NMR. spectroscopy.     

Synthesis of unsymmetrical 4,6-diarylpyrimidines

Unsymmetrical 4,6-diarylpyrimidines were synthesized using Suzuki coupling reaction via selective arylation of 4,6-dichloropyrimidine.     

Preparative synthesis of 4,6-dinitroanthranil

A preparative method for the synthesis of 4,6-dinitroanthranil by intramolecular cyclization of 2-azido-4,6-dinitrobenzaldehyde was developed.     

Carbenoid reactions of 2-halomethyl-4,6-dimethyl-s-triazines

Reactions of lithium, sodium, and potassium salts of 2,4,6-trimethyl-s-triazine (1) with 2-halomethyl-4,6-dimethyl-s-triazine (2) (X = Cl, Br) in glyme have been studied and found to give 1,2-bis(4,6-dimethyl-s-triazin-2-yl)ethane (3), 1,2-bis(4,6-dimethyl-s-triazin-2-yl)ethene (5), 1,2,3-tris(4,6-dimethyl-s-triazin-2-yl)cyclopropane (6), 1,2,3-tris(4,6-dimethyl-s-triazin-2-yl)propane (7), and 1,2,3,4-tetrakis(4,6-dimethyl-s-triazin-2-yl)butane (8). It is proposed that product 3 is formed primarily via an S(N)2 reaction, whereas the remaining products are formed primarily via carbenoid reactions that are enumerated.     

Vicarious nucleophilic amination of five-membered 4,6-dinitrobenzoheterocycles

Russian Chemical Bulletin - Reactions of isomeric 4,6-dinitro-1- and 4,6-dinitro-2-phenylindazoles, as well as 4,6-dinitro-2-phenylbenzo[b]furan, with various aminating agents were studied under...     

Preparation of Partially Hydrogenated 4,6‐Dimethyldibenzothiophenes

The synthesis of three key intermediates of the hydrogenation pathway in the hydrodesulfurization of 4,6‐dimethyldibenzothiophene (4,6‐DM‐DBT; 1 ) is described. The hydrogenated derivatives 1,2,3,4‐tetrahydro‐4,6‐dimethyldibenzothiophene (= 4,6‐dimethyl‐1,2,3,4‐tetrahydrodibenzothiophene; 4,6‐DM‐TH‐DBT; 2 ), 1,2,3,4,4a,9b‐hexahydro‐4,6‐dimethyldibenzothiophene (= 4,6‐dimethyl‐1,2,3,4,4a,9b‐hexahydrodibenzothiophene; 4,6‐DM‐HH‐DBT; 3 ), and dodecahydro‐4,6‐dimethyldibenzothiophene (= 4,6‐dimethylperhydrodibenzothiophene; 4,6‐DM‐PH‐DBT; 4 ) were prepared by direct hydrogenation of 1 . The reactions were carried out in continuous and batch reactors by using metal sulfide as well as noble‐metal catalysts. The influence of the reaction conditions on the formation of the products and the distribution of their stereoisomers was studied in detail. The isomers of the main products were isolated and characterized by NMR, GC/MS/MS, and X‐ray crystal‐structure diffractometry.     

Synthesis of 4,6-dimethyl-tetrahydro- and hexahydro-dibenzothiophene

2-Bromo-3-methylcyclohexanone was synthesized by conjugate addition of trimethylaluminium to 2-bromo-2-cyclohexen-1-one with copper bromide as catalyst, coupled with 2-methylthiophenol and annulated with the aid of polyphosphoric acid to 4,6-dimethyl-1,2,3,4-tetrahydrodibenzothiophene. The latter was hydrogenated to 4,6-dimethyl-1,2,3,4,4a,9b-hexahydrodibenzothiophene, another intermediate in the hydrodesulfurization of 4,6-dimethyldibenzothiophene, by zinc and trifluoroacetic acid, and dehydrogenated to 4,6-dimethyldibenzothiophene.     

Reaktionen des 4,6-Dichlor-5-formylpyrimidins

Zusammenfassung Bei der Methanolyse des 4,6-Dichlor-5-formylpyrimidins (I) tritt neben dem 4,6-Dimethoxy-5-formylpyrimidin (III) auch das 4-Methoxy-6-hydroxy-5-formylpyrimidin (IV) als Reaktionsprodukt [in Verhältnis 11] auf. Das Aldoxim V des 4,6-Dichlor-5-formylpyrimidins ist instabil und geht in das 4-Chlor-5-cyano-6-hydroxypyrimidin (VI) über. Beide Reaktionen werden mit Hilfe möglicher Zwischenprodukte erklärt. Hingegen führt Methanolyse des Dimethylacetals von I in guter Ausbeute zum 4,6-Dimethoxy-5-formylpyrimidin (III). Das 4,6-Dichlordimethylacetal (II) wird durch aufeinanderfolgende Sulfanilamidolyse, Methanolyse und Hydrolyse in das Acetal des 4-Sulfanilamido-6-methoxy-5-formylpyrimidins (IX) verwandelt. Die gleiche Reaktionsfolge wird auch mit dem cyclischen Acetal 5-(2-Dioxolano)-4,6-dichlorpyrimidin zu XII durchgeführt.

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During methanolysis of 4.6-dichloro-5-formylpyrimidine (I) 4-methoxy-6-hydroxy-5-formylpyrimidine (IV) is formed as well as 4,6-dimethoxy-5-formylpyrimidine (III) in a ratio of 11. The aldoxime V of 4,6-dichloro-5-formylpyrimidine is not stable and is converted into 4-chloro-5-cyano-6-hydroxypyrimidine (VI). Both reactions are interpreted by considering possible intermediates. On the other hand, methanolysis of the dimethylacetal of I affords a good yield of 4,6-dimethoxy-5-formylpyrimidine (III). The 4,6-dichlorodimethylacetal (II) is converted into the acetal of 4-sulfanilamido-6-methoxy-5-formylpyrimidine (IX) by sulfanilamidolysis followed by methanolysis and hydrolysis. The same series of reactions has also been applied to the cyclic acetal of 5-(2-dioxolano)-4,6-dichloropyrimidine to give XII.

     

Nitration of 2-substituted pyrimidine-4,6-diones,structure and reactivity of 5,5-gem-dinitropyrimidine-4,6-diones

Nitration of some 2-substituted pyrimidine-4,6-diones in sulfuric acid was studied, which afforded previously unknown 5,5-gem-dinitropyrimidine-4,6-diones in high yields. The gem-dinitro products were easily attacked by nucleophiles with concomitant formation of gem-dinitroacetyl derivatives, which in turn could be further hydrolyzed to salts of dinitromethane and triureas.     

Synthesis of diimine ligands with cycloalkyl substituents based on 4,6-dibenzofuran-and 4,6-dibenzothiophenedicarboxaldehydes

A formic acid-catalyzed reaction of substituted cycloalkylanilines with 4,6-dibenzofuran-and 4,6-dibenzothiophenedicarboxaldehydes in methanol-dichloromethane mixture afforded a number of the corresponding diimines, which can be of interest as components of catalytic systems for polymerization of olefins. Dedicated to the memory of Academician N. N. Vorozhtsov on the 100th anniversary of his birth. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1131–1134, June, 2007.     

Synthetic utilization of polynitroaromatic compounds. 2. Synthesis Of 4,6-dinitro-1,2-benzisothiazol-3-ones and 4,6-dinitro-1, 2-benzisothiazoles from 2-benzylthio-4,6-dinitrobenzamides

Cyclization of 2-benzylthio-4,6-dinitrobenzamides to 4,6-dinitro-1, 2-benzisothiazol-3-ones was achieved using SO(2)Cl(2) in CH(2)Cl(2) at room temperature. Alkylation of these heterocycles proceeded in a nonregioselective manner to yield a mixture of corresponding O- and N-alkylated products. Oxidation of 4,6-dinitro-1,2-benzisothiazoles (50% H(2)O(2) in AcOH) afforded the corresponding S-oxides and S, S-dioxides, depending on oxidation conditions. Unexpectedly, oxidation of a 3-methoxy derivative resulted in ring opening with the formation of the corresponding sulfamide. Chlorination of these 4,6-dinitro-1,2-benzisothiazol-3-ones (PCl(5)-POCl(3)) gave the expected 3-chloroisothiazoles.     

A Convenient Synthesis of 4,6-Dichloro-5-benzylthiopyrimidine

A practical and convenient two-step synthesis of the title compound 4,6-dichloro-5-benzylthiopyrimidine (3) from 4,6-dihydroxypyrimidine (1) is described.     

Nucleophilic displacement of hydrogen in 4,6-dinitro--benzofuroxan and -benzofupazan. Synthesis of some novel 7-substituted 4,6-dinitro-benzofuroxans and -benzofurazans.

Formal hydride ion displacement readily occurs in 4,6-dinitro-benzofuroxan and -benzofurazan. This process provides a simple two-step synthesis of some new 7-substituted-4,6 dinitro derivatives.     

Crystal-stabilisation of an elusive 4,6-pyrimidinedione dimer

The formation of a disproportionation dimer of 4,6-pyrimidinedione 1, 2-(4,6-dioxo-5-pyrimidinyl)-4,6-dioxo-1,2,3,5,5-pentahydropyrimidine 2, results from the reactivity of the inner-salt tautomers or ions of 1, contrasting to the general properties of nucleobases which are all stable in the lactam or dilactam molecular forms. The observation of dimer 2, indefinitely stable in the crystalline state, reveals an unusual chemical reactivity strongly dependent on the H-tautomeric forms of the substrate and product.     

5,5'-Methylenebis(4,6-dihydroxy-2-methylthiopyrimidines)

5,5'-Methylenebis(4,6-dihydroxy-2-methylthiopyrimidines) were synthesized by condensation of 4,6-dihydroxy-2-methylthiopyrimidine with formaldehyde and aromatic or heterocyclic aldehydes in ethanol. According to the spectral data and PM3 quantum-chemical calculations, the most favorable tautomers of 5,5'-methylenebis(4,6-dihydroxy-2-methylthiopyrimidine) are those stabilized by intramolecular hydrogen bonds between the OH group of one pyrimidine fragment and the CÍO groups of the other.     

Synthesis of 4,6‐Dimethyldibenzothiophene and 1,2,3,4‐Tetrahydro‐4,6‐dimethyldibenzothiophene via Tilak Annulation

1,2,3,4‐Tetrahydro‐4,6‐dimethyldibenzothiophene was prepared by coupling 2‐bromo‐3‐methylcyclohexanone with 2‐methylbenzenethiol and annulating the product with the aid of polyphosphoric acid. A mixture of 1,2,3,4‐tetrahydro‐4,6‐dimethyldibenzothiophene and 4,6‐dimethyldibenzothiophene was prepared by coupling 2‐bromo‐3‐methylcyclohex‐2‐en‐1‐one with 2‐methylbenzenethiol and annulating the product with the aid of polyphosphoric acid. 2‐Bromo‐3‐methylcyclohexanone was synthesized by conjugate addition of Me₃Al to 2‐bromocyclohex‐2‐en‐1‐one with CuBr as catalyst and 2‐bromo‐3‐methylcyclohex‐2‐en‐1‐one by bromination? elimination of 3‐methylcyclohex‐2‐en‐1‐one. 1,2,3,4,4a,9b‐Hexahydro‐4,6‐dimethyldibenzothiophene was prepared by reduction of 1,2,3,4‐tetrahydro‐4,6‐dimethyldibenzothiophene with Zn and CF₃COOH.     

5,5'-Arylmethylenebis(2-amino-4,6-dihydroxypyrimidines)

Condensation of 2-amino-4,6-dihydroxypyrimidine with aromatic aldehydes at 100-110°C in DMSO gave a series of 5,5'-arylmethylenebis(2-amino-4,6-dihydroxypyrimidines).     

Oxidation of 2-dialkylaminomethyl-4,6-di-tert-butylphenols

Oxidative transformations of 2-dialkylaminomethyl-4,6-di-tert-butylphenols depend on the nature of the oxidant, the character of the substituents at the nitrogen atom, and the medium. A mechanism of the oxidation of these compounds is suggested. The molecular structure of the compound obtained as a result of oxidative trimerization of 2-dimethylaminomethyl-4,6-di-tert-butylphenol was established by X-ray structural analysis. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1328–1335, July, 1997.     

Synthesis,structure, and characterization of high-energy 4,6-diazido-N-(4,6-diazido-1,3,5-triazin-2-yl)-1,3,5-triazin-2-amine

Chemistry of Heterocyclic Compounds - The high-energy compound 4,6-diazido-N-(4,6-diazido-1,3,5-triazin-2-yl)-1,3,5-triazin-2-amine was obtained in high yield by azidation of...     

Synthesis of some 4-substituted and 4,6-disubstituted dibenzothiophenes

The synthesis is described of various 4-substituted ( 1 ) and 4,6-disubstituted ( 2 ) dibenzothiophenes by lithiation reactions. The factors controlling the formation of 4,6-disubstituted dibenzothiophenes by the lithiation of 4-methyl- and 4-ethyl-dibenzothiophene at the 6-position versus lithiation at the α-carbon of the 4-substituent are examined.