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

โœ Scribed by A. Nishinaga; K. Nakamura; T. Matsuura

Publisher
Elsevier Science
Year
1981
Tongue
French
Weight
210 KB
Volume
22
Category
Article
ISSN
0040-4039

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โœฆ Synopsis

Base-catalyzed reaction of 5-acylmethyl-2,5-di-t-butyl-4-oxa-2-cyclopentenones selectively derived from 4-alkyl-2,6-di-t-butylphenols via three steps involving oxygenation, acetylation, and acid-treatment gave 3-alkyl-2,5-di-t-butyl-2,4-cyclopentadienones in excellent yield. Previously, we have reported a one-step method for the synthesis of 3-substituted 2,5-di-tbutyl-2,4-cyclopentadlenones involving t-BuOK-catalyzed oxygenation of 4-aryl-2,6-di-t-butyl-and 2,4,6-tri-t-butyl-phenols in t-BuOH at 70 oC.293 This method is based on characteristic reactivity of these phenols that under the reaction conditions they are oxygenated selectively at the ortho position affording epoxy-g-quinols, which undergo base-catalyzed intramolecular decomposition to give the cyclopentadienones.4

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