Selective One‐Step Aerobic Oxidation of Cyclohexane to ϵ‐Caprolactone Mediated by <i>N</i>‐Hydroxyphthalimide (NHPI)

Abstract

Abstract The selective one‐step aerobic oxidation of cyclohexane to ϵ‐caprolactone was achieved in the presence of N ‐hydroxyphthalimide (NHPI) and aldehyde under mild conditions. Remarkably, 12 % of cyclohexane was converted with a selectivity of 77 % of ϵ‐caprolactone and 15 % of KA oil. Control experiments indicated that NHPI accelerated the oxidation of aldehydes and peroxy radicals generated from aldehydes in situ were the key intermediates in the period of CH bond activation. 2,2,6,6‐Tetramethylpiperidine 1‐oxyl (TEMPO) addition and a series of m ‐chloroperoxybenzoic acid ( m ‐CPBA) oxidation experiments showed that the oxidation proceeded via a complex radical chain mechanism.