Constituents of the higher fungi. Part VII. The photodimerisation of hispidin analogues; a proton magnetic resonance study

Abstract

Proton magnetic resonance spectroscopy is used to show that the photodimerisation of hispidin analogues proceeds by addition across the olefinic double bond of the styryl residue and a double bond in the pyrone ring to give a cyclobutane derivative. Probable structures are given for the dimers from hispidin tri-O-methyl ether, and from the 4-methoxy-6-(2-, 3-, and 4-methoxymethoxystyryl)-2-pyrones.