LAUSR

Rearranged cage ketones 6a and 6b are reported in eight linear synthetic steps starting with 2,5-dimethoxybenzaldehyde 9 without the involvement of protecting groups. In this regard, Diels‒Alder reaction, [2+2]photocycloaddition and Lewis acid promoted rearrangement with BF3OEt2 has been used as key steps. Surprisingly, during the ring expansion process with Lewis acid, solvent incorporation occurred. This rearrangement approach has provided difficult complex targets via non-obvious synthetic routes. Rearrangement process demonstrated here opens up a new synthetic strategy to interesting and unusual cage molecules.