Rearrangement with degradation of the carbon skeleton

In 1944 Criegee110 observed that benzoyl 4a-decalyl peroxide was re-arranged by heat to an isomer for which the structure of a benzoylated hemi-acetal was proved  

Benzoyl 4a-decalyl peroxide (m.p. 67-68° 0.28 g) was boiled for 1 min with pyridine hydrochloride (0.2 g) in pyridine (2 ml). After cooling, the mixture was poured into dilute sulfuric acid, and the precipitated oil was placed in a refrigerator for crystallization. This afforded ll-oxabicyclo[4.4.1]undecan-l-yl benzoate (0.15 g) which after recrystallization from aqueous methanol had m.p. 96-97°. 

This reaction is an example of the fission of a carbon-carbon bond that had been known for some time previously to occur with many organic peroxides. This occurs, for instance, in the industrially important acid fission of cumyl hydroperoxide ( %, %-dimethylbenzyl hydroperoxide) to phenol and acetone, as follows 111 

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