Photo-Fries-type rearrangement of cyclic enamides. An efficient route to structurally diverse five-membered enaminones.

A simple, efficient and user-friendly protocol for the preparation of structurally diverse enaminones from enamides has been developed. The strategy is based on a photo-induced intramolecular Fries-type rearrangement. The photochemical transformation proceeds under mild reaction conditions, applies to a broad substrate range, is highly economic, and limits the amount of waste produced. The proposed methodology was used as a key step in the synthesis of dihydrojasmone an important fragrance compound.