α-Santonin: Photochemie in protischen Lösungsmitteln und Pyrolyse

In protic media of the type R? OH and R? COOH irradiation of α-santonin yields addition products of the isophotosantonic-lactone type 3 apart from lumisantonin ( 2 ) and in some cases its photoproducts. The amount of 3 depends on the acidity of the solvent up to a limiting value, above which exoanhydro-isophotosantonic-lactone ( 5 ) is also formed. Under pyrolytic conditions α-santonin is in equilibrium with pyrosantonin ( 14 ), the structure of which is discussed.