Phototriggered Butenolide Formation from a Cyclobutenedione and an Acidic Nucleophile

A phototriggered conjugation reaction of an aminocyclobutenedione and a nucleophile was discovered. Upon irradiation of the materials with a blue LED, a butenolide derivative with substituents derived from the aminocyclobutenedione and the nucleo-phile was produced. Acidic nucleophiles were favorable for the reaction, and the reaction proceeded efficiently under organic solvent or organic solvent/aqueous buffer (1/1) conditions. This reaction would be useful for synthesis of unique butenolide derivatives and derivatization of acidic functional groups.