Composition of products and mechanism of the reaction of ozone with 2,6-di(tert-butyl)-4-methylphenol

It was shown that two series of products with opening and with preservation of the aromatic nucleus are formed in the reaction of ozone with ionol, and a mechanism was proposed for the reaction.N. N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, 117334 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 5, pp. 1203–1207, May, 1992.     

Formation of radical pairs in the photolysis of 2, 6-di(tert-butyl)-l,4-benzoquinonediazide in single crystals of 2,6-di(tert-butyl)-4-methylphenol

In the photolysis of single crystals of 2,6-di(tert-butyl)-4-methylphenol with the addition of 2,4-di(tert-butyl)-l,4-benzoquinonediazide it was found that they form carbenes and radical pairs with r₁=6.0 å, which are secondary products of the photolysis of the quinonediazide and which form as a result of transfer of a hydrogen atom from the phenol to the carbene. The high thermal stability of these radical pairs makes it possible to use them as two-spin probes. Also found were radical products that are annealed by light with wavelength greater than 560 nm and are hypothetically classified as ion-radical pairs with r_av=8.9 å.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 560–564, March, 1991.     

Coordination chemistry of 2,6-bis(diphenylphosphorylmethyl)-4-methylphenol

The trifunctional ligand, 2,6-bis(diphenylphosphorylmethyl)-4-methylphenol (L ₂), forms complexes with cerium(III) nitrate having a ligand to metal ratio of 1: 1, 2: 1, and 3: 1. The structures of these complexes in the solid state and in solution were studied by X-ray diffraction, IR and NMR (¹H and ³¹P) spectroscopy, and conformational analysis (molecular mechanics). The 2: 1 complexes of L ₂ with lanthanum(III) and neodymium(III) nitrates were synthesized and characterized. In all complexes, the neutral ligand is coordinated through both phosphoryl oxygen atoms. The hydroxy oxygen atom is coordinated only in some complexes, and the hydrogen atom of the hydroxy group is involved in hydrogen bonding. The compositions and structures of the resulting complexes depend on the method of synthesis and the nature of solvent. The ligand was found to undergo easy inner-sphere oxidation. The structure of one of the transformation products was established by X-ray diffraction. Unlike the coordinated ligand, the free ligand is very stable to oxidation. Dedicated to Corresponding Member of the Russian Academy of Sciences T. A. Mastryukova. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2440–2454, November, 2005.     

CoMFA and CoMSIA studies on 1,3-bis(benzylidene)-3,4-dihydro-1H-naphthalen-2-one, 2,6-bis(benzylidene)cyclohexanone, and 3,5-bis(benzylidene)-4-piperidone series of cytotoxic compounds

A number of 1,3-bis(benzylidene)-3,4-dihydro-1H-naphthalen-2-ones, 2,6-bis(benzylidene)cyclohexanones, and 3,5-bis(benzylidene)-4-piperidones possess significant potencies toward L1210, Molt 4/C8, and CEM cell lines. The objective of the current 3D QSAR study is to discover some of the structural parameters which govern cytotoxic potencies. The CoMFA models with steric and electrostatic fields provided satisfactory statistical data [(r2cv = 0.485, r2ncv = 0.834, r2pred = 0.591), (r2cv = 0.532, r2ncv = 0.850, r2pred = 0.729), and (r2cv = 0.561, r2ncv = 0.864, r2pred = 0.666)] in regard to the cytotoxic potencies observed toward L1210, Molt 4/C8, and CEM cell lines, respectively. The CoMSIA model with steric, electrostatic, hydrophobic, and H-bond donor fields exhibited r2cv = 0.513, r2ncv = 0.833, and r2pred = 0.562 for cytotoxic activity toward L1210 cells, while the best CoMSIA models were obtained by a combination of steric, electrostatic, and hydrophobic fields which yielded statistically significant data [(r2cv = 0.531, r2ncv = 0.828, r2pred = 0.652) and (r2cv = 0.560, r2ncv = 0.841, r2pred = 0.729)] to explain the cytotoxicity toward Molt 4/C8 and CEM cells, respectively. The information obtained from the CoMFA and CoMSIA 3D contour maps can be used in the design of more potent cytotoxins.     

Phosphorus-containing derivatives of 2,6-di(tert-butyl)phenol: The antioxidant activity and properties of the corresponding phenoxyl radicals

The properties of phenoxyl radicals generated by the oxidation of mono-, di-, and triphosphorus derivatives of 2,6-di(tert-butyl)-4-methylphenol (ionol) were studied by ESR. These compounds exist as conformers that are interconvertible with a temperature-dependent rate. Numerical processing of the ESR spectra gave the thermodynamic and activation parameters that characterize the interconversion of the conformers. The antioxidant activities of the compounds were studied in a model oxidation of oleic acid and with biological objects. These phenols efficiently inhibited radical oxidation reactions. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 744–750, April, 2007.     

Reaction of 3,6-di(tert-butyl)-4-chloro-1,2-benzoquinone with N,N-disubstituted dithiocarbamates

A reaction of 3,6-di(tert-butyl)-4-chloro-1,2-benzoquinone with disubstituted N,N-dithiocarbamates leads to zwitterionic compounds containing 2-iminio-1,3-dithiole ring annulated to the quinone skeleton. These products reversibly add acids, giving salts of the corresponding catechols; they form complexes with copper involving oxygen atoms, as well.     

Cyclization-elimination of 2-phenyldimethylsiloxy-4,6-di(tert-butyl)phenol

A study was carried out on the cyclization-elimination of 2-phenyldimethyl-siloxy-4,6-di(tert-butyl)phenol, which very selectively leads to the formation of benzene and dimethyl [3,5-di(tert-butyl)-o-phenylenedioxy]silicon. This reaction is described by a first-order kinetic equation. The acceleration of the reaction in the presence of organic bases is related to their catalytic action.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2643–2645, November, 1990.     

Complexation of copper(II) with 2,6-bis(dimethylaminomethyl)-4-methylphenol in the presence of surfactants

Complexation of copper(II) with 2,6-bis(dimethylaminomethyl)-4-methylphenol (HA) in water-alcohol solutions (40 vol % isopropanol) and in solutions of surfactants of different types is studied by potentiometric titration, spectrophotometry, and mathematical modeling of the equilibria. In the media studied (pH 5.5–10.5), nine copper(II) complexes with neutral and deprotonated ligands are found, that is, eight mononuclear complexes and one tetranuclear complex. The addition of surfactant affects both the composition and the stability of formed copper(II) complexes, although an unambiguous dependence of the composition of complex on the medium nature is not revealed. At equal and relatively low concentrations of complexing agent (\(C_{Cu^{2 + } } \) = 0.6 mM) and ligand (C _HA = 1.6 mM), the formation of [Cu₄A₂]⁶⁺ complex is promoted by a nonionic surfactant Triton X-100 (TX) and a cationic surfactant cetyltrimethylammonium bromide. In water-alcohol solutions, this complex is formed at higher concentrations of reagents, i.e., at 1.94 and 5 mM, respectively. The [Cu(HA)₂]²⁺ complex, which occurs in all of the four media studied, is the most stable in solutions of an anionic surfactant sodium dodecyl sulfate. In alkaline medium (pH ≈ 9–10), when concentration conditions are identical (C _HA = 1.6 mM, \(C_{Cu^{2 + } } \) = 0.58 mM), redox interactions take place only in the presence of a cationic surfactant (C _CTAB = 0.5 and 5 mM) to form the copper(I) oxide precipitate. In solutions of nonionic surfactant, the precipitate is formed at higher concentrations of complexing agent (\(C_{Cu^{2 + } } \) = 1.9 mM) and ligand (C _HA = 5 mM). When stored in air, copper(I) oxide precipitate is dissolved in mother liquor.     

Synthesis and structure of 4,6-di(tert-butyl)-2-(4-chloro-7,8-dimethylquinolin-2-yl)-7-(piperidin-1-ylmethyl)-1,3-tropolone

Russian Chemical Bulletin - The reaction of 4-chloro-2,7,8-trimethylquinoline with 4,6-di(tert-butyl)-3-(piperidin- 1-ylmethyl)-1,2-benzoquinone, which was prepared by the in situ oxidation of...     

2,6-Diarylhexahydro-4-pyridazinols by acid-catalyzed cyclization of benzaldehyde aryl-2-(2-propenyl)hydrazones

Treatment of benzaldehyde l-(2-propenyl)-4-methylsulfonylphenylhydrazone ( 1f ) with 45% sulfuric acid gave 2-(4-methylsulfonylphenyl)-6-phenylhexahydro-4-pyridazinol ( 2f ) in 35% yield rather than the expected 1-(4-methylsulfonylphenyl)-1-(2-propenyl)hydrazine. The halogen-substituted hydrazones 1c-1e and benzaldehyde 1-(2-methyl-2-propenyl)phenylhydrazone ( 1b ) gave similar results.     

Acetyl chloride-3,5-di(tert-butyl)-4-hydroxy-N,N-dimethylbenzylamme salt in the benzylation of organic and inorganic sulfur-containing compounds

The reactions of the quaternary acylammonium salt formed on treatment of3,5-di-tertbutyl-4-hydroxy N,N-dimethylbenzylamine with acetyl chloride, with various organic and inorganic sulfur-containing compounds were studied. The possibility of using this salt for the introduction of a sterically hindered phenol moiety in various sulfur-containing compounds was shown.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 98–102, January, 1994.     

Reaction of 2,6-di(bromomethyl)-1,4-dihydropyridine with β-alanine

Latvian Institute of Organic Synthesis, Riga. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1701–1702, December, 1995. Original article submitted September 28. 1995.     

Synthesis of 2,6-di(pyrazol-1-yl)-4-bromomethylpyridine, and its conversion to other 2,6-di(pyrazol-1-yl)pyridines substituted at the pyridine ring

Two routes to 2,6-di(pyrazol-1-yl)-4-hydroxymethylpyridine (1) from 2,6-dihydroxy-isonicotinic acid, in four and six steps, are reported. Reaction of 1 with 48% HBr yields 2,6-di(pyrazol-1-yl)-4-bromomethylpyridine (2), which is a powerful precursor to a range of new tridentate ligands for transition metals functionalised at the pyridine ring. As a proof of principle, we describe the further elaboration of 2 to give two 2,6-di(pyrazol-1-yl)pyridines bearing nucleobase substituents, and the back-to-back ligand 1,2-bis[2,6-di(pyrazol-1-yl)pyrid-4-yl]ethane. Crystal structures of two of these new derivatives are presented.     

Reductive cyclization of 1-(2-nitroaryl)isoquinoline derivatives

Isoquinoline derivatives 3b and 3c were prepared and their triethyl phosphite mediated reductive cyclization reactions investigated. Only the indazolo[3,2-a]isoquinolines 4b and 4c were formed.     

Synthesis of N-(2-carboxy-4-nitroaryl)-β-alanines and their cyclization to quinoline derivatives

N-(2-Carboxy-4-nitroaryl)-β-alanines were obtained by reaction of 2-chloro-5-nitrobenzoic acids with β-alanine. The products were converted to the corresponding 1,2,3,4-tetrahydro-4-oxo-6-nitroquinolines by cyclization.     

Coordination polymers based on CuII and MnII complexes with 2-hydroxy-3,6-di(tert-butyl)-1,4-benzoquinone

The reactions of Mn^II and Cu^II ions with deprotonated 2-hydroxy-3,6-di(tert-butyl)-1,4-benzoquinone (L) afford bis(chelates) ML₂. In the solid phases of the compounds, the coordinated ligands L perform the bridging function leading to the formation of polymer structures: layered in MnL₂ and framework in CuL₂. In the coordination units ML₂ the chelate fragments are in the trans and cis positions relative to one another for MnL₂ and CuL₂, respectively. Paramagnetism of the polymer structures MnL₂ and CuL₂, for which the effective magnetic moments in the high-temperature region are 5.85 and 1.91 μ_B, respectively, is determined by the metal ions, because the energy level of the triplet state of the coordinated L lies much higher, according to the calculated data, than that of the singlet state.     

Crystal structure of bis(2-(2-thiazolylazo)-4-methylphenol)cobalt(III)chloride.

The reaction between CoCl2 x 6H2O and 2-1-(2-thiazolylazo)-p-cresol (TAC) in acetone resulted in six coordinated cobalt(III) complex, [Co(TAC)2]Cl3. Two TAC ligands coordinate with cobalt ion forming four five membered chelate rings. The cobalt ion is octahedrally coordinated by a phenolic oxygen, azo nitrogen and nitrogen in thiazole rings. Three chloride ions are disordered.     

Generation and Reactions of Lithiated tert-Butyl and 2,6-Di(tert-butyl)-4-methylphenyl Cyclopropanecarboxylates

tert-Butyl and 2,6-di(tert-butyl)-4-methylphenyl (BHT) cyclopropanecarboxylates ( 4 , 6 , 24 , 25 ) are lithiated with LiN(i-Pr)₂ and t-BuLi, respectively. Reactions with alkyl halides, aldehydes, acyl chlorides, and heteroelectrophiles give α-substituted BHT esters which can be cleaved (t-BuOK/H₂O/THF) to the corresponding carboxylic acids or reduced (LiAlH₄/THF) to the cyclopropanemethanols.