Decomposition of an oxodiazirine: free versus incarcerated within the cavities of two α-cyclodextrins

The chemistry of oxodiazirine 1 was investigated by photolyzing its α-cyclodextrin (6-Cy) complex, for which a Job plot indicated a 1:2 guest-to-host stoichiometry. Solid-phase photolysis of 1@(6-Cy)2 produced tricyclo[3.3.0.02,8]octan-3-one (3) and bicyclo[3.3.0]oct-5-en-3-one (4) in a 93:7 ratio. In contrast, gas-phase thermolysis of free 1 resulted in a 47:53 ratio of products 3 and 4. Thus, incarceration of a guest compound within a fitting microenvironment of two host molecules leads to a strongly enhanced chemoselectivity, even when highly reactive species, such as carbenes, are involved.