Oxygenation of 2,6-di-t-butylphenols bearing electron-withdrawing group at 4-position mediated by Co(II)-schiff base complex

4-Acyl-2,6-di-$\text{t}$-butylphenols except 3,5-di-$\text{t}$-butyl-4-hydroxybenzaldehyde were oxygenated in the presence of Co(Salpr) exclusively at the ortho position to give the corresponding 3,5-di-$\text{t}$-butyl-6-hydroperoxy-2,4-cyclohexadienone derivatives in quantitative yield.     

Reaction of superoxo Co(III) complexes with 2,6-di-t-butyl-p-benzoquinone methides

Superoxo Co(III) complexes derived from Co(Salpr) and [Co(CN)₅]^3? reacted with 2,6-di-$\text{t}$-butyl-$\text{p}$-benzoquinone methides to give 2,6-di-$\text{t}$-butyl-$\text{p}$-benzoquinone and 2,6-di-$\text{t}$-butyl-2,5-cyclohexadienonespirooxiranes as the main products, which are considered to result from nucleophilic attack by the superoxo species on the exo double bond of the quinone methides.     

New 1,1-amino hydroperoxides from regioselective oxygenation of 4-(n-arylmethyleneamino)-2,6-di-t-butylphenols.

The oxygenation of 4-(N-arylmethyleneamino)-2,6-di-$\text{t}$-butylphenols with Co(Salpr), a five coordinate Co(II0 Schiff base complex, in CH₂Cl₂ results in the regioselective hydroperoxylation at the imino carbon to give N-(l-aryl-l-hydroperoxymethyl)-3,5-di-$\text{t}$-butyl-$\text{p}$-benzoquinone monoimines, which give exclusively the corresponding amides and 2,6-di-$\text{t}$-butyl-$\text{p}$-benzoquinone in an aerobic solution of KOH in 90% EtOH.     

A new route to 3-alkyl-2,5-di-t-butyl-2,4-cyclopentadienones from 4-alkyl-2,6-di-t-butylphenols

Base-catalyzed reaction of 5-acylmethyl-2,5-di-$\text{t}$-butyl-4-oxa-2-cyclopentenones selectively derived from 4-alkyl-2,6-di-$\text{t}$-butylphenols $\text{via}$ three steps involving oxygenation, acetylation, and acid-treatment gave 3-alkyl-2,5-di-$\text{t}$-butyl-2,4-cyclopentadienones in excellent yield.     

Acylation of 4-substituted 6-hydroperoxy-2,6-di-t-butyl-2,4-cyclohexadienones

Acylation of 4-aryl-2,6-di-$\text{t}$-butyl- and 2,4,6-tri-$\text{t}$-butyl- 6-hydroperoxy-2,4-cyclohexadienones gave unexpected products, 4-acyloxy-5,6-epoxy-2-cyclohexenones and 2-acyloxy-5,6-epoxy-3-cyclohexenones. The reaction involves a rapid homolysis of the peroxy bond of peroxy esters transiently formed in the pre-existing slow step.     

Selective formation of peroxy-p-quinolato Co(III) complexes in the oxygenation of 4-alkyl-2,6-di-t-butylphenols with Co(II)-Schiff's base complexes

The oxygenation of 4-alkyl-2,6-di-$\text{t}$-butylphenols ($\text{2}$) with Co(II)-Schiff's base complexes in aprotic solvents such as CH₂Cl₂, THF, Py, and DMF leads to highly selective formation of the corresponding peroxy-$\text{p}$-quinolato Co(III) complexes. The reaction proceeds by mechanism involving a rate determining hydrogen abstraction by superoxo Co(III) species from $\text{2}$ giving phenoxy radical, rapid step of electron transfer from Co(II) complex to the phenoxy radical, and dioxygen incorporation into phenolato Co(III) complex thus formed.     

Oxygenation of 2,6-di-t-butylphenols with superoxo Co(III) complexes

Superoxo Co(III) complexes, [Co(CN)₅O₂][X]₃ where X = Et₃N⁺ and (Ph₃P)₂N⁺, mediate the dioxygen incorporation into 2,6-di-$\text{t}$-butylphenols ($\text{1}$) with the same regioselectivity as that in the base-catalyzed oxygenation of $\text{1}$. The superoxo species acts as a base but is not incorporated into the substrate.     

Mechanism of selective p-quinol formation in the cobalt schiff base complex-catalyzed oxygenation of 4-alkyl-2,6-di-t-butylphenols

The selective formation of $\text{p}$-quinols in the Co(Salpr)-catalyzed oxygenation of 4-alkyl-2,6-di-$\text{t}$-butylphenols in MeOH has been found to involve the rate determining reduction of peroxy-$\text{p}$-quinolato Co(III) complex formed in the initial fast step. An ionic mechanism of the reduction of the OO bond in the peroxy complex by MeOH has been discussed based on kinetic studies. The reactive species in the catalytic cycle is found to be [Co(III)(Salpr)(OH)].     

Towards tetrasilabicyclo[1.1.0]butane: reductive coupling of 1-t-butyl-2,2-dimesityl-1,1,2-trichlorodisilane

Reductive coupling of 1-$\text{t}$-butyl-2,2-dimesityl-1,1,2-trichlorodisilane employing Li-naphthalenide furnishes, on oxygenation or hydrolysis of the reaction mixture, products ($\text{8}$-$\text{11}$) that may arise from insertion of oxygen into or the addition of water across the Si-Si bonds of 1,3-di-$\text{t}$-butyl-2,2,4,4-tetramesityltetrasilabicyclo-[1.1.0]butane ($\text{3}$).     

Vapour pressure of binary,three-phase (S-L-V) systems and solubility

Solubilities and vapour pressures along the solid-liquid equilibrium line for systems 2-t-butyl-4-methylphenol+benzene, 2-t-butyl-4-methylphenol+cyclohexane, 2,6-di-t-butyl-4-methylphenol+benzene, 2,6-di-t-butyl-4-methylphenol+cyclohexane and enthalpies of fusion for six phenols have been measured.The effect of specific interactions, leading to association, on solubilities and vapour pressures of 13 binary three-phase systems (S—L—V) has been discussed. Results of solubility prediction from vapour pressure measurements and vice versa are presented.     

Biomimetic entry to acyclic terpene synthesis a novel rearrangement of allyl ether catalyzed by organoaluminium reagents

The intramolecular prenyltransfer reaction is accomplished by the rearrangement of allyl ethers with (2,6-di-$\text{tert}$-butyl-4-methylphenoxy)methylaluminum trifluoromethanesulfonate. The present method provides a simple and highly efficient synthesis of lavandulol.     

Conformation,in solution,of c-4-t-butyl-1-phenyl-r-1-(N-piperidyl)cyclohexane hydrochloride. The conformational energy of t-butyl

Although the hydrochloride of $\text{c}$-4-$\text{t}$-butyl-1-phenyl-$\text{c}$-1-(N-piperidyl)cyclohexane crystallizes in the conformation with axial $\text{t}$-butyl, it exists as an almost equimolar mixture of the two chair conformers in CD₂ Cl₂ solution. The position of equilibrium allows one to calculate ΔG°_{$\text{t}$-Bu} as ?4.9 kcal/mol.     

Synthesis of 1-[(2-hydroxy-1-(hydroxymethyl)ethoxy)methyl]-1,2,4-triazole-3- and 5-carboxamides

Coupling of trimethylsilyl derivative of methyl 1,2,4-triazole-3-carboxylate with 2-$\text{O}$-(chloromethyl)-1,3-di-$\text{O}$-benzyl glycerol, followed by amination and removal of the protecting groups afforded 1-[(2-hydroxy-1-(hydroxymethyl)ethoxy)methyl]-1,2,4-triazole 3- and 5-carboxamides, 1a and 1b, respectively.     

Halogenation of n-substituted p -quinone monoimines and p -quinone monooxime esters: VIII. Halogenation of N -aroyl(arylsulfonyl)-2,6-di- tert -butyl-1,4-benzoquinone monoimines and their reduced forms

Chlorination of N-aroyl(arylsulfonyl)-2,6-di-tert-butyl-1,4-benzoquinone imines gave Z and E isomers of 4-arylsulfonylimino-2,6-di-tert-butyl-5,6-dichlorocyclohex-2-en-1-ones and Z isomers of 4-aroyl-(arylsulfonyl)imino-2,6-di-tert-butyl-5,5,6-trichlorocyclohex-2-en-1-ones, in which the tert-butyl group on the sp ³-hybridized carbon atom occupies exclusively the axial position. The formation of Z/E-isomeric structures is related to configurational stability of the chlorination products. The chlorination of 4-aroylamino-2,6-di-tertbutylphenols was found to be accompanied by replacement of one tert-butyl group by chlorine atom with formation of 4-aroylimino-6-tert-butyl-2,3,5,6-tetrachlorocyclohex-2-en-1-ones. Original Russian Text ? A.P. Avdeenko, V.V. Pirozhenko, O.V. Shishkin, G.V. Palamarchuk, R.I. Zubatyuk, S.A. Konovalova, O.N. Ludchenko, 2008, published in Zhurnal Organicheskoi Khimii, 2008, Vol. 44, No. 6, pp. 818–824. For communication VII, see [1].     

Reaction of peroxy-p-quinol acetates with trifluoroacetic anhydride. Formation of new oxepinone derivatives.

The reaction of peroxy-$\text{p}$-quinol acetates derived from 4-R-2,6-di-$\text{t}$-butylphenols (R = Me, Et, n-Pr, s-Bu) with trifluoroacetic anhydride gives the corresponding 2-tri-fluoroacetylmethylidene-5-oxepinone derivatives. A favoured mechanism involves efficient conversion of a quinoxy cation intermediate primarily formed into an oxepinone derivative to which a trifluoroacetyl group is incorporated.     

Tetrahydropyridines and furans from the reaction of 4-t-butylpyridine 1-oxide with t-butyl and 1-adamantyl mercaptan

The reaction of 4-t-butylpyridine 1-oxide (1) with t-butyl or 1-adamantyl mercaptan in acetic anhydride yielded the expected 2- and 3-alkylthio-4-t-butylpyridines and 1-acetyl-2,6-bis-(alkylthio)-3-acetoxy-4-t-butyl- and the unexpected 1-acetyl-2-acetoxy-3,6-bis(alkylthio-4-t-butyl-1,2,3,6-tetrahydropyridines. The addition of t-butyl mercaptan to a solution of 1 in acetic anhydride containing triethylamine produced the expected 1-acetyl-2-t-dmtylthio-3-acetoxy-4-t-butyl-6-hydroxy-1,2,3,4-tetrahydropyridine ( 6a ) and the unexpected 1-acetyl-2,6-bis(hydroxy)-3-t-butylthio-4-t-butyl-1,2,3,6-tetrahydropyridine. Mild alkaline hydrolysis of 6a yielded predominantly 2-[(acetamido) (t-butylthio)methyl]-3-t-butyl-5-hydroxy-2,5-dihydrofuran. The latter was converted by very mild acidic reagents to the corresponding furan and with 2,4-dinitrophenylhydrazine and sulfuric acid furnished 3-t-butylfurfural 2,4-dinitrophenyl-hydrazone.     

Electron transfer reactions between pentafluorobenzoyl peroxide and dimethoxybenzenes

Pentafluorobenzoyl peroxide (FBP) reacted rapidly with dimethoxybenzenes in F₁₁₃ (CCl₂FCClF₂) with kinetics of first order in each component. High yields of ring-substituted esters of $\text{m}$-dimethoxybenzene ($\text{m}$-DMB) and $\text{p}$-dimethoxybenzene ($\text{p}$-DMB) were obtained, whereas for 2,5-di-$\text{t}$-butyl-1,4-dimethoxybenzene (DBDMB), the $\text{t}$-Bu group was simultaneously eliminated. For 2,5-dimethyl-1,4-dimethoxybenzene (DMDMB), the benzylic hydrogen was substituted. Rate and product studies both indicate a rate-determining electron transfer step leading to radical ion pairs which collapse to products.     

Dissociation energies of O–H bonds in alkylseleno- and alkyltelluro-substituted phenols

The O?H bond dissociation energy (D _O?H) has been determined for eight alkylseleno-substituted phenols, one alkyltelluro-substituted phenol, and one alkyltelluro-substituted pyridinol. D _O?H has been estimated by the intersecting-parabolas method from kinetic data using five reference compounds: α-tocopherol (D _O?H = 330.0 kJ/mol), 3,5-di-tert-butyl-4-methoxyphenol (D _O?H = 347.6 kJ/mol), 4-methylphenol (D _O?H = 361.6 kJ/mol), 2,6-di-tert-butyl-4-methylthiophenol (D _O?H = 336.3 kJ/mol), and 2,6-di-ter-tbutyl-4-methylphenol (D _O?H = 338.0 kJ/mol). The following D _O?H values (kJ/mol) have been obtained: 335.9 for 2,5,7,8-tetramethyl-2-phytyl-6-hydroxy-3,4-dihydro-2H-1-benzoselenopyran, 342.6 for 2-methyl-5-hydroxy-2,3-dihydrobenzoselenophene, 333.5 for 2,4,6,7-tetramethyl-5-hydroxy-2,3-dihydrobenzoselenophene, 339.4 for 2-tert-butyl-4-methoxy-6-octylselenophenol, 357.9 for dodecyl 3-(4-hydroxyphenyl) propyl selenide, 348.5 for dodecyl 3-(3,5-dimethyl-4-hydroxyphenyl)propyl selenide, 350.9 for dodecyl 3-(3-tert-butyl-4-hydroxyphenyl)propyl selenide, 338.0 for dodecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propyl selenide, 343.0 for 2,6-di-tert-butyl-4-(tellurobutyl-4′-phenoxy)phenol, and 338.8 for 6-octyltelluro-3-pyridinol. The stabilization energies of phenoxyl radicals containing R substituents (X = O, S, Se, Te) have been compared.     

Steric effects on forming different by-products in the formylation reaction of 2,4-dialkylphenol (dialkyl = t-Bu/t-Bu, t-Bu/Me and Me/Me) proved by their structural and spectral characterizations

In the formylation reaction of 2,4-dialkylphenol (2,4-di-tert-butylphenol, 2-tert-butyl-4-methylphenol and 2,4-dimethylphenol) in the presence of hexamethylenetetramine, steric effects of alkyl groups play important roles in forming different types of by-products, namely 2,4-di-tert-butyl-6-[(6,8-di-tert-butyl-2H-1,3-benzoxazin-3(4H)-yl)methyl]phenol (1), 2-tert-butyl-4-methyl-6-[(6-tert-butyl-8-methyl-2H-1,3-benzoxazin-3(4H)-yl)methyl]phenol (2) and tris(2-hydroxy-3,5-dimethylbenzyl)amine hydrochlorate (3). These three compounds are fully characterized and single-crystal structures of 1 and 3 are further elucidated.     

Oxidative dimerization of 2,6-Di-tert-butyl-4-(2-hydroxyethyl)phenol

2,6-Di-tert-butyl-4-(2-hydroxyethyl)phenol undergoes oxidative self-coupling by the action of K₃Fe(CN)₆ in alkaline medium at room temperature to give 7,9-di-tert-butyl-4-(3,5-di-tert-butyl-4-hydroxyphenyl)-1-hydroxymethyl-2-oxaspiro[4.5]deca-6,9-dien-8-one. The composition of the reaction products has been determined, and the mechanism of their formation is discussed.