Oxasecoalkylation chain extension

The fragmentation is stereospecifically anti as shown by complementary geometry obtained in the cleavage of the epimeric pair of epoxycyclobutanones 91 and 92 (Eq. 110). The fragmentation product 93 of cyclobutanone 91 is transformable into the dimethyl ester of the pheromone of the Monarch butterfly. Considering the availability of the starting epoxy ketones from enones, the oxasecoalkylation serves to reorient the oxidation pattern with chain extension as summarized in Eq. 111. 

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