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25.1.2.2.4 Variation 4: Oxidation of Alcohols with a Nitroxide and a Co-oxidant

DOI: 10.1055/sos-SD-025-00010

Podlech, J.Science of Synthesis, (20072541.

Although other nitroxides have been recommended, mostly as catalytic reagents,[‌117‌] only 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO) finds wide application for the oxidation of alcohols 25 to aldehydes 26 (see Scheme 19).[‌118‌,‌119‌] It may be used in catalytic amounts together with sodium hypochlorite, calcium hypochlorite,[‌117‌] sodium bromite,[‌117‌] Oxone,[‌120‌] N-chlorosuccinimide,[‌18‌] (diacetoxyiodo)benzene,[‌121‌‌123‌] or copper(II) chloride[‌21‌] as stoichiometric co-oxidants. Reactions in which (diacetoxyiodo)benzene is used can be accelerated by the addition of 1mol% methanesulfonic acid.[‌121‌] Utilization of oxygen as a co-catalyst for an oxidation with 2,2,6,6-tetramethylpiperidin-1-oxyl is described in Section 25.1.2.2.5. Unfortunately, care must be taken when using 2,2,6,6-tetramethylpiperidin-1-oxyl as it is a toxic irritant, which is readily absorbed through the skin.

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References


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