Amination of 4,6- and 2,4-dichloropyrimidines with polyamines

Amination of a double excess of 4,6-dichloropyrimidine with various diamines in the presence of cesium carbonate in boiling dioxane quantitatively afforded the corresponding N,N′-bis(6-chloropyrimidin-4-yl) derivatives, while its reactions with tri- and tetraamines gave N,N′,N″-tris- and N,N′,N″,N‴-tetrakis(6-chloropyrimidin-4-yl) derivatives. Equimolar amounts of 2,4-dichloro- or 4,6-dichloropyrimidine and diamines reacted in the presence of Pd(0) complexes to form macrocyclic compounds containing pyrimidine fragments. Catalytic reactions of 4 equiv of diamines with 4,6-dichloropyrimidine can lead to the formation of 4,6-bis-(diamino)pyrimidines. Relations between the yield and the nature of diamine and catalytic system were found.     

A novel synthesis of 4,6-dimethyl- and diphenyl-2,5-dihydro-1,3,5,2-triazaphosphorines

The synthesis of 2,5-dihydro-1,3,5,2-triazaphosphorines via the intramolecular cyclization of N,N'-phos-phinylacetamidines or benzamidines is described. These derivatives represent the sole examples of 4,6-dialkyl or diaryl substitutions of this ring system.     

Hydrogen bonding in 2‐amino‐4,6‐dimethoxypyrimidine, 2‐benzylamino‐4,6‐bis(benzyloxy)pyrimidine and 2‐amino‐4,6‐bis(N‐pyrrolidino)pyrimidine: chains of fused rings and a centrosymmetric dimer

Molecules of 2‐amino‐4,6‐di­methoxy­pyrimidine, C₆H₉N₃O₂, (I), are linked by two N—H?N hydrogen bonds [H?N 2.23 and 2.50 Å, N?N 3.106 (2) and 3.261 (2) Å, and N—H?N 171 and 145°] into a chain of fused rings, where alternate rings are generated by centres of inversion and twofold rotation axes. Adjacent chains are linked by aromatic π–π‐stacking interactions to form a three‐dimensional framework. In 2‐­benzylamino‐4,6‐bis(benzyloxy)pyrimidine, C₂₅H₂₃N₃O₂, (II), the mol­ecules are linked into centrosymmetric R(8) dimers by paired N—H?N hydrogen bonds [H?N 2.13 Å, N?N 2.997 (2) Å and N—H?N 170°]. Molecules of 2‐amino‐4,6‐bis(N‐pyrrolidino)­pyrimidine, C₁₂H₁₉N₅, (III), are linked by two N—H?N hydrogen bonds [H?N 2.34 and 2.38 Å, N?N 3.186 (2) and 3.254 (2) Å, and N—H?N 163 and 170°] into a chain of fused rings similar to that in (I).     

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.     

1,3-Dipolar cycloaddition reactions of 4,6-diazaphenanthrene 6-phenacylide

Summary The 1,3-dipolar cycloaddition reactions of 4,6-diazaphenanthrene 6-phenacylide formed in situ from the appropriate quaternary bromide in basic medium were investigated; as dipolarophiles acrylonitrile, ethyl acrylate,n-butyl acrylate and diethyl maleate were used.

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1,3-Dipolare Cycloadditionsreaktionen von 4,6-Diazaphenanthren-6-phenacylid

Zusammenfassung Es wurden die 1,3-dipolaren Cycloadditionen von 4,6-Diazaphenanthren-6-phenacylid untersucht, welches in situ aus dem entsprechenden quaternären Bromid in Gegenwart von Alkali dargestellt wurde. Als Dipolarophile wurden Acrylnitril, Ethylacrylat,n-Buthylacrylat und Diethylmaleat eingesetzt.

     

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.     

Functionalization of 4,6-dinitro-2-phenylindole at position 7

Transformation of the amino group in 7-amino-1-methyl-4,6-dinitro-2-phenylindole afforded a number of new 7-R-4,6-dinitroindoles and a first representative of a novel tricyclic heteroaromatic system of [1,2,5]oxadiazolo[4,3-g]indole. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1508–1511, July, 2008.     

Die photochemische Reduktion von 4,6-Dimethyl-2-pyrimidinol

π,π*-Excitation of 4,6-dimethyl-2-pyrimidinol in methanol leads to an addition product 5 whereas in 2-propanol a dihydrodimer 3 is formed. By acid catalysis the dihydrodimer gives the 5, 9-methano-2H-pyrimido[5,6-e] [1,3]diazepine-2,7(1H)-dione 7 which with stronger acids rearranges to the 2H-cyclopentapyrimidin-2-one 8 . Nitrous acid reacts with the dihydrodimer yielding the dioxime of 2-hydroxy-4,6-pyrimidinedicarbaldehyde.     

Synthesis and Properties of 4,6-Dimethyl-5-pentyl-2-thioxo-1,2-dihydropyridine-3-carbonitrile and 3-Amino-4,6-dimethyl-5-pentylthieno[2,3-b]pyridines

The reaction of 3-pentylpentane-2,4-dione with cyanothioacetamide afforded 4,6-dimethyl-5-pentyl-2-thioxo-1,2-dihydropyridine-3-carbonitrile. Alkylation of the latter led to the formation of 2-alkylsulfanyl-4,6-dimethyl-5-pentylpyridine-3-carbonitriles or 3-amino-4,6-dimethyl-5-pentylthieno[2,3-b]pyridines, depending on the alkylating agent and reaction conditions. The structures of the key compounds were proved by 2D NMR spectroscopy and X-ray analysis. Biological activity of the synthesized compounds was evaluated in silico. Some compounds were experimentally found to stimulate growth of sunflower seedlings.

     

2-amino-4,6-lutidineN-oxide complexes formed from various copper(II) salts

Summary Copper(II) complexes of 2-amino-4,6-lutidineN-oxide (4,6DMAH) have been isolated as tetrafluoroborate, nitrate, chloride and bromide salts, and characterized by spectral methods (i.e., i.r., u.v.-vis. and e.s.r.). Variation of the ligand-to-copper(II) ratio yielded solids having the following empirical formulae: [Cu(4,6DMAH)₄]X₂ (X=BF₄), [Cu(4,6DMAH)₂X₂] (X=NO₃, Cl) and [Cu(4,6DMAH)X₂] (X=Br). In addition, a deprotonated ligand complex, Cu(4,6DMA)₂, was prepared using copper(II) acetate. The Sigand usually binds to the copper(II) centresvia theN-oxide oxygen and only the deprotonated ligand coordinatesvia the exocyclic nitrogen as well as the TV-oxide oxygen. The complexes involving coordinated anions and at least two ligands are monomeric while Cu(4,6DMAH)Br₂ is polymeric. The ring substituents affect either the stoichiometry or the stereochemistry of these solids when compared to less sterically demanding 2-aminopyridineN-oxides.     

Synthesis and reactions of 4,6-dimethoxyindole,an unusual indole system

A synthesis of 4,6-dimethoxyindole is described. Formylation or oxalylation reactions gave substitution at position 7 rather than the usual 3-substitution characteristic of other indoles. A synthesis of N,N-dimethyl-4,6-dimethoxytryptamine is presented along with NMR data for 3 and 7-substituted compounds in this series.     

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 2[(4,6-diphenyl-2H-pyran-2-ylidene)methyl]-4,6-diphenylpyrylium perchlorate

The title compound was prepared by the condensation of 4,6-diphenyl-2H-pyran-2-one and acetophenone in phosphorus oxychloride. The absorption spectrum of this 2,2-methine dye is compared with those of the corresponding 2,4- and 4,4-methine dyes.     

Reaction of some coumarin and 4,6-diaryl-2H-pyran derivatives with secondary amines

The reaction of piperidine, morpholine, piperazine or dimethylamine with several coumarins, 3-bromocoumarin, 4,6-diaryl-2H-pyran-2-ones and 3-bromo-4,6-diaryl-2H-thiopyran-2-ones gave o-hydroxycinnamic acid amides, benzofurans, open-chain δ-oxoamides and thiophene derivatives, respectively.     

Reaction of fullerene C60 with 2-azido-4,6-diphenylpyrimidine

The first representative of the pyrimidine-substituted [60]fullereno[1,2-b]aziridines was synthesized by the reaction of fullerene C₆₀ with 2-azido-4,6-diphenylpyrimidine. 2-(Azahomo[60]fullereno)-4,6-diphenylpyrimidine was found to be formed as a by-product. The electrochemical properties of the adducts were studied.     

Observations on the electron impact induced fragmentation of methyl and phenyl 4,6-O-Benzylideneglucopyranosides

The structure of some rearrangement ions in the electron impact induced fragmentation of methyl 4,6-O-benzylidene-2,3-di-O-methyl-α-D -glucopyranoside and phenyl 4,6-O-benzylidene-2,3-di-O-methyl-β-D -glucopyranoside have been investigated using high resolution, deuterium labelling and linked scan (B,E) techniques. Shifts of methoxyl groups from C-2 and C-3 to C-1 have been confirmed.     

Synthesis and xanthine oxidase inhibitory activity of 4,6-disubstituted 1-p-chlorophenylpyrazolo[3,4-d]pyrimidines

Several 4,6-disubstituted 1-p-chlorophenylpyrazolo[3,4-d]pyrimidines were prepared from 4,6-dichloro-1-p-chlorophenylpyrazolo[3,4-d]pyrimidine and their xanthine oxidase inhibitory activity were tested in vitro.     

Azines and Azoles: CXXI. Alkylation of 5,7-Dihydro-4H-pyrano[2,3-d:6,5-d']- dipyrimidine-4,6(3H)-dione and Its 5-Phenyl Derivative

Methylation of 5,7-dihydro-4H-pyrano[2,3-d:6,5-d']dipyrimidine-4,6(3H)-dione and its 5-phenyl analog with dimethyl sulfate in the presence of LiOH in aqueous solution gives rise to the corresponding 3,7-dimethyl derivatives. The same isomers are formed by methylation of 5-phenyl-5,7-dihydro-4H-pyrano[2,3-d:6,5-d']dipyrimidine-4,6(3H)-dione with methyl iodide in the presence of K2CO3 in N,N-dimethylacetamide. However, with ethyl bromide, propyl iodide, or butyl bromide instead of methyl iodide, mixtures of 3,7- and 1,7-dialkyl-5-phenyl-5,7-dihydro-4H-pyrano[2,3-d:6,5-d']dipyrimidine-4,6-diones were obtained.     

Synthesis of substituted 2-amino-4,6-bis(nonafluoro-tert-butyl)-1,3,5-triazines

A procedure was developed for the synthesis of substituted 2-amino-4,6-bis(nonafluoro-tert-butyl)-1,3,5-triazines from 2-chloro-4,6-bis(nonafluoro-tert-butyl)-1,3,5-triazine and aliphatic and aromatic amines. The data of¹⁹F NMR spectroscopy are indicative of the presence of a barrier to internal rotation. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1568–1572, August, 1999.     

4,6-Dihydroxysalicylic Acid-Catalyzed Oxidative Olefination of Methyl N-Heteroarenes with Benzyl Amines

Benzyl amines were deaminated for the olefination of methyl N-heteroarenes such as quinolines, benzothiazoles, and quinoxalines catalyzed by 4,6-dihydroxysalicylic acid with only 1 mol % catalyst loading. A wide range of N-heteroaryl stilbenoids were synthesized in yields of 42 to 96 % using oxygen (1 atm) as the sole oxidant. 4,6-dihydroxysalicylic acid not only behaves as an organocatalyst for the oxidation of benzyl amines to the imine intermediates, but also provides an acidic reaction condition for the olefinations. Gram scale reaction and the synthesis of two pharmaceutically relevant conjugated olefins were also successful using this methodology.