- Cyclohexadienone diazeniumdiolates from nitric oxide addition to phenolates
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Sterically hindered phenols react with nitric oxide under basic condititons to give either cyclohexadienone diazeniumdiolates or oximates. Phenols with 2,6-di-tert-butyl and 4-methyl (butylated hydroxy toluene, BHT), 4-ethyl, or 4-methoxy methylene substituents yield the corresponding 2,6-di-tert-butyl-2,5-cyclohexadienone-4-alkyl-4-diazeniumdiolate salts (4-methyl 1a, 4-ethyl 3a, 4-methoxymethylene 5a). Phenols with 2,6-di-tert-butyl and 4-methylene (2,6-di-tertbutylphenol) substituents yield 4-methoxymethylenediazeniumdiolate (5a) together with 2,6-di-tert-butyl benzoquinone oximate (6a), while phenols with 2,6-di-tert-butyl and 4-methylenedimethylamino or hydrogen substituents yield exclusively 2,6-di-tert-butyl benzoquinone oximate (6a). Alkylation of the silver salts of 1a, or treating the O2-protonated diazeniumdiolate with diazomethane, both yield mixtures of O1- and O2-methylated isomers. All the compounds exhibit exothermic thermal decomposition except the quinuclidinium (1e, 3e, 5e) and triethylenediammonium (1f) salts which decompose endothermically. Three of the compounds namely 'O2-protonated' (Z)-1-[4-(2,6-di-tert-butyl-4-methyl-cyclohexadienonyl)]diazen-1-ium-1,2-diol inic acid (1b), O2-methyl (Z)-1-[4-(2,6-di-tert-butyl-4-methyl-cyclohexadienonyl)]diazen-1-ium-1,2-diol ate (1c), and 'O2-protonated' (Z)-1-[4-(2,6-di-tert-butyl-4-methoxymethylenecyclohexadienonyl)]diazen-1-ium -1,2-diolinic acid (5b) were characterized by single-crystal X-ray diffraction studies. The diazeniumdiolate framework in all the structures is coplanar with considerable π-bonding delocalized over the O-N-N-O framework.
- Scott Bohle,Imonigie, Jerome A.
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- Discovery and SAR study of 3-(tert-butyl)-4-hydroxyphenyl benzoate and benzamide derivatives as novel farnesoid X receptor (FXR) antagonists
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3-(tert-Butyl)-4-hydroxyphenyl 2,4-dichlorobenzoate (1) was discovered in our in-house high throughput screening as a moderate FXR antagonist. To improve the potency and the stability of the hit 1, forty derivatives were synthesized and SAR was systematically explored. The results turn out that replacing the 2,4-dichlorophenyl with 2,6-dichloro-4-amidophenyl shows great improvement in potency, replacing the benzoate with benzamide shows improvement in stability and slight declining of potency and 3-(tert-butyl)-4-hydroxyphenyl unit is essential in obtaining the FXR antagonistic activity.
- Song, Kebiao,Xu, Xing,Liu, Peng,Chen, Lili,Shen, Xu,Liu, Junhua,Hu, Lihong
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p. 6427 - 6436
(2015/10/05)
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- Synthesis and crystal structure determination of 2,6-di-tert-butyl-4-(2,4, 6-triphenylpyridinium-1-yl)phenolate and its corresponding perchlorate salt
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2,6-Di-tert-butyl-4-(2,4,6-triphenylpyridinium-1-yl)phenolate belongs to the class of negatively solvatochromic dyes commonly used for the empirical determination of solvent polarities. By way of exception, it crystallizes without any solvent of crystallization due to the presence of two bulky tert-butyl groups in the phenolate moiety. The synthesis of this hydrophobic betaine dye has been improved and an X-ray crystal structure analysis of this solventless zwitterionic dye and its protonated form (as a perchlorate salt) has been carried out.
- Shekhovtsov, Sergey V.,Omelchenko, Irina V.,Dyakonenko, Viktoriya V.,Shishkin, Oleg V.,Allmann, Rudolf,Libor, Thomas,Reichardt, Christian,McHedlov-Petrossyan, Nikolay O.
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experimental part
p. 1394 - 1399
(2012/03/27)
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- New insights into the reactivity of nitrogen dioxide with substituted phenols: A solvent effect
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Various alkyl-substituted phenols react readily with nitrogen dioxide (.NO2) in different solvents at room temperature. In all cases nitration is the major reaction and leads to the formation of mono- and dinitrophenols and 4-nitrocyclohexa-2,5-dienones from 2,4,6-tri-substituted phenols. Oxidation, dimerisation and, in one case, nitrosation are also observed. The reaction pathway followed changes according to the solvent and to the nature and the number of substituents on the phenolic ring. Wiley-VCH Verlag GmbH & Co. KGaA, 2005.
- Astolfi, Paola,Panagiotaki, Maria,Greci, Lucedio
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p. 3052 - 3059
(2007/10/03)
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- Photolysis of N-Alkoxybenzoquinone Imine N-Oxides
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Photolyses of a series of N-alkoxybenzoquinone imine N.oxides give products arising mainly from alkyl radicals, the solvent, and the several quinonoid species present in the reaction mixture.The alkyl radicals may be derived by fragmentation of the corresponding alkoxynitrenes which also rearrange to nitroso-compounds and hence to oximes.
- Baldry, Peter J.,Forrester, Alexander R.,Ogilvy, Munro M.,Thomson, Ronald H.
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p. 2035 - 2040
(2007/10/02)
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- PREPARATION OF α,β-UNSATURATED CARBOXYLIC ACID ESTERS BY THE REACTION OF ACI-NITROESTERS WITH ETHOXYCARBONYLMETHYLENETRIPHENYLPHOSPHORANE
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The reaction of ethoxycarbonylmethylenetriphenylphosphorane with aci-nitroesters derived from 2,6-di-t-butyl-4-nitrophenol and alcohols afforded α,β-unsaturated carboxylic esters.When mono-aci-nitroester of 1,3-butanediol or 1,6-hexanediol was used, (E)-ethyl 5-hydroxy-2-hexenoate or (E)-ethyl 8-hydroxy-2-octenoate was obtained.
- Mitsunobu, Oyo,Kimura, Junji,Shimizu, Tatsuhiko,Kawashima, Atsushi
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p. 927 - 930
(2007/10/02)
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