Manganese(III) acetate mediated catalytic oxidation of substituted dioxolene and phenols

• MnIII acetate catalytically oxidizes 3,5-di-tert-butylcatechol to quinone with high turnover.
• Oxidation of DTBC to DTBQ goes through a MnIV-semiquinone species as per ESI-MS data.
• MnIII acetate also efficiently catalyzes oxidation of 2-aminophenol to 2-aminophenoxazinone.
• MnIII acetate oxidatively couples sterically hindered phenols to yield biaryls.

Manganese(III) acetate is found to be an efficient catalyst to perform oxidation of 3,5-di-tert-butylcatechol (DTBC) to 3,5-di-tert-butylbenzoquinone (DTBQ) and 2-aminophenol (OAP) to 2-aminophenoxazinone (APX). The kcat values are 1.72(2) × 103 and 2.8(2) × 102 h−1 for the formation of DTBQ and APX, respectively. The turnover number of APX formation is highest among the synthetic mimics. ESI-MS studies of DTBC oxidation suggest formation of a MnIV intermediate. Manganese(III) acetate is also capable of oxidative CC bond coupling in sterically hindered phenols to form biaryls in 65–94% yield.

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