Intramolecular [2+2] Photocycloaddition and Cycloreversion of Ferulic Acid Derivatives

Abstract

ABSTRACT : Intramolecular photocycloaddition of ferulic acid derivatives proceeded in high yields to give head-to-head intramolecular photodimers as three atropisomers. The photocycloaddition was sensitized by triplet sensitizers such as benzophenone, whereas photocycloreversion was promoted by 9,10-dicyanoanthracene (DCA) as an electron-transfer photocatalyst. On the other hand, intermolecular photocycloaddition afforded a head-to-tail photodimer. Scheme 1 Recently, much attention has been focused on the chemical and biological properties of ferulic acid derivatives including the anti-carcinogenesis and the anti-oxidation. 1 We have recently found a convenient method for the mass production of ferulic acid from the oily component of rice bran, which contribute to the eco chemistry. 2 Ferulic acid ( 1 ) and its derivatives are expected to be photochemically reactive, because the inter- and intra-molecular photocycloaddition of cinnamic acid and its derivatives have been widely investigated from the synthetic and mechanistic viewpoints. The topochemical intermolecular photocyclodimerization of cinnamic acid in solid states,