Demethylenation of Cyclopropanes via Photoinduced Guest‐to‐Host Electron Transfer in an M6L4 Cage

Unusual demethylenation reactions of cyclopropanes under UV‐light irradiation were found within a cavity of a photoactive coordination cage. The reaction proceeded via a guest‐to‐host electron transfer owing to the highly electron‐deficient nature of the cage. The reactions were highly chemoselective and enabled late‐stage derivatization of a steroid molecule, which led to a totally new un‐natural steroid. Cage power has enabled a unique reaction with the demethylenation of cyclopropanes initiated by guest‐to‐host electron transfer under irradiative conditions. The reaction proceeds with remarkable chemoselectivity and high yields.