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• 950-99-2 2,2,5,7,8-pentamethylchroman-6-ol 

Relevant academic research and scientific papers

Potassium t-Butoxide-catalysed Oxygenation of an α-Tocopherol Model Compound 2,2,5,7,8-Pentamethylchroman-6-ol

The potassium t-butoxide-catalysed oxygenation of an α-tocopherol model compound, 2,2,5,7,8-pentamethylchroman-6-ol, gave 5-hydroxy-2,2,5,7,8-pentamethylchroman-6(5H)-one (2) and 7,8-dihydro-5,7-dihydroxy-8-methylene-2,2,5,7-tetramethylchroman-6(5H)-one, and 6-hydroxy-2,2,6,7,8-pentamethylchroman-5(6H)-one which was found to be formed as the result of the acyloin rearrangement of (2).

Potassium tert-Butoxide-catalysed Oxygenations of Vitamin E and its Model Compound 2,2,5,7,8-Pentamethylchroman-6-ol

Oxygenation of vitamine E in tetrahydrofuran in the presence of potassium tert-butoxide under oxygen gave products 2a, 3a, 4a, 5a and 6a arising from oxidation of the aromatic moiety.Under similar conditions, a vitamin E model compound, 2,2,5,7,8-pentamethylchroman-6-ol 1b, gave the analogous products 2b, 3b, 4b, 5b and 6b.Initial attack at the 5 position leads to the acyloin 6b, which is converted into the isomer 5b.The hydroperoxide 7b is derived from the acyloin 5b and transformed into the 7-methylene compound 3b.The 8-methylene compound 2b is converted into the carbolactone 4b.The molecular structures of compounds 2b, 3b, 4b and 7b were confirmed X-ray crystallographic analysis.Possible reaction pathways for the product formation and relationships between the product distribution and the basicity of reaction media are discussed.

Oxygenations of Vitamin E (α-Tocopherol) and Its Model Compound. 2,2,5,7,8-Pentamethylchroman-6-ol, in the Presence of Potassium Superoxide Suspended in Tetrahydrofuran and Unusual Acyloin Rearrangements

In the presence of potassium superoxide (KO2) suspended in tetrahydrofuran under an oxygen atmosphere, α-tocopherol (vitamin E) (1) was converted to 6-hydroxy-2,6,7,8-tetramethyl-2-(4',8',12'-trimethyltridecyl)chroman-5(6H)-one (2) and 5-hydroxy-2,5,7,8-tetramethyl-2-(4',8',12'-trimethyltridecyl)chroman-6(5H)-one (3), and a vitamin E model compound, 2,2,5,7,8-pentamethylchroman-6-ol (4), to 6-hydroxy-2,2,6,7,8-pentamethylchroman-5(6H)-one (5) and 5-hydroxy-2,2,5,7,8-pentamethylchroman-6(5H)-one (6).By the use of oxygen-18, molecular oxygen was found to be incorporated into a ketonic group in 5 and a hydroxy group in 6.Since 5 was derived from 4 and since 3 and 6 were converted to 2 and 5, respectively, in the presence of KO2 quantitatively, an acyloin rearrangement is shown to occur in the formation of the end products, 2 and 5.On treatment of potassium hydroxide suspended in tetrahydrofuran, 4 gave 5 though its yield was low.Thus, the intermediates, 3 and 6, are considered to result from the base-catalyzed oxygenations of 1 and 4, respectively.The striking characteristic of the KO2-catalyzed reactions is that the products are obtained in high yield and, in particular, 5 and 6 in quantitative yield.A possible mechanistic scheme for the KO2-catalyzed oxygenation of vitamin E is proposed.Due to the basicity of KO2, 1 gives rise to α-tocopherolate.The reaction of the α-tocopherolate with molecular oxygen leads to its derivative bearing a hydroperoxy group at C5.The O-O bond cleavage of the hydroperoxide, followed by hydrogen abstraction, affords 3, which undergoes acyloin rearrangement to yield 2.