Synthetic experiments in the benzopyrone series Part LXVI. Relative stability of isomeric 6-methyl and 8-methyl-trihydroxy flavones

Abstract

8-Methyl baicalein has been made (1) from 8-methyl chrysin by the preparation of the 6-aldehyde and subsequent Dakin's reaction and (2) from C-methyl phloracetophenone dimethyl ether by steps involving persulphate oxidation and flavone ring closure. The isomeric 6-methyl compound has been obtained by the nuclear methylation of norwogonin and demethylation with aluminium chloride. The methyl ethers of the former undergo only demethylation when boiled with hydriodic acid whereas those of the latter undergo isomeric change besides demethylation.