Structures of oxidation products of 4,6-di-tert-butylpyrogallol |
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Authors: | A I Shif S N Lyubchenko O Ya Borbulevych O V Shishkin K A Lyssenko L P Olekhnovich |
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Institution: | (1) Scientific Research Institute of Physical and Organic Chemistry at Rostov State University, 194/2 prosp. Stachki, 344090 Rostov-on-Don, Russian Federation;(2) Department of Chemistry, Rostov State University, 7 ul. Zorge, 344090 Rostov-on-Don, Russian Federation;(3) A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, 28 ul. Vavilova, 117813 Moscow, Russian Federation;(4) Institute for Single Crystals, National Academy of Sciences of the Ukraine, 60 prosp. Lenina, 310001 Kharkov, Ukraine |
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Abstract: | Oxidation of 4,6-di-tert-butylpyrogallol gave two dimeric products instead of the expected 4,6-di-tert-butyl-3-hydroxy-1,2-benzoquinone (2). It was established by X-ray diffraction analysis that the first product has the structure
of tetra-tert-butyl-6, 10a-dihydroxy-1,2-dioxo-3,4a,7,9-1,2,4a, 10a-tetrahydrodibenzo-1,4-dioxine. From this it follows that compound 2
undergoes regio- and stereospecific dimerization according to the 2π+4π]-cycloaddition mechanism,viz, the hetero Diels—Alder reaction. The double intensities of the signals in the1H NMR spectrum are indicative of a symmetrical structure of the second product, 2,6,4′, 6′-tetra-tert-butyl-4,4′-dihyroxy-3,5,3′,5′-tetraoxo-4,4′-bi(cyclohexene), which is a racemate of enantiomers formed upon recombination
(r+r orl+l) of the intermediate of oxidation of pyrogallol, namely, of ther,l-stereogenic 3,5-di-tert-butyl-1-hydroxy-2,6-dioxocyclohex-3-enyl radical.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 139–146, January, 1999. |
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Keywords: | 4 6-di-tert-butylpyrogallol 3 4a 7 9-tetra-tert-butyl-6 10a-dihydroxy-1 2-dioxo-1 2 4a 10a-tetrahydrodibenzo-1 4-dioxine 4 6-di-tert-butyl-3-hydroxy-1 2-benzoquinone 2 6 4′ 6′ -tetra-tert-butyl-4 4′ -dihydroxy-3 5 3′ 5′ -tetraoxo-4 4′ -bi(cyclohexene) Diels— Alder reaction X-ray diffraction study molecular structure |
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