Die Oxydation von (+)‐(4 R )‐4, 8‐Dimethyl‐nonanol‐(1) mit Blei (IV)‐ acetat

The lead tetraacetate oxidation of the optically active aliphatic alcohol 1 in benzene afforded the tetrahydrofurane derivative 3 and the 3‐acetoxy‐tetrahydro‐pyranes 4 – 6 as major products. The formation of the expected compound 3 in racemic form is interpreted by the stepwise sequence a → b → c → d 1–3 → e. The appearance of a carbonium ion of type d 3 in the conversion 1 → 3 is in contrast to the direct oxydative ring closure (cf. c → e ) which had been postulated previously for cases involving alicyclic educts with sterically fixed reaction centres. The same carbonium ion d 3 is considered as a possible intermediate in the formation of compounds 4 – 6 (cf. f → g → h ). The latter process represents a novel type of reaction of monohydric alcohols with lead tetraacetate.