The structure of isopannarin

Abstract

The structure proposed by Yosioka for the product obtained by the treatment of the depsidone pannarin (2-chloro-3-hydroxy-8-methoxy-1,6,9-trimethyl-11-oxo-11H-dibenzo[b,e][1,4]dioxepin-4-carbaldehyde) (2) with concentrated sulfuric acid is revised to 5-chloro-6-hydroxy-4'-methoxy-2',4,5'-trimethyl-3,6'-dioxo- 2,3 -dihydrospiro[benzofuran-2,1'- cyclohexa - 2',4'- dienel-7-carbaldehyde (5).