The freeradicals 3-ethoxy-2-(ethoxycarbonyl)-3-oxopropyl (1.) and 3-ethoxy-2-(ethoxycarbonyl)-2-methyl-3-oxopropyl (2.) were generated by photolysis of perester precursors in i) hexane solution, ii) in the presence of β-cyclodextrin, and iii) in NaY zeolite. While freeradicals in solution are reluctant to rearrange, they do so when encapsulated in β-cyclodextrin or NaY zeolite. The coenzyme-B12-dependent