Synthesis of Bioactive Natural Polymethoxyflavones and Their Vinyl Ether Derivatives

Bioactive natural polymethoxyflavones 1-6 and their vinyl ether derivatives 7-15 were synthesized by bromination, aromatic nucleophilic substitution, methylation, benzyl protection, Friedel-Crafts acetylation, aldol condensation, cyclization, DDQ dehydrogenation, regioselective demethylation, debenzylation and O-prenylation or O-farnesylation with resorcinol and appropriate substituted benzaldehydes as starting materials. Among them, compounds 7-15 are new compounds. Natural products 2-4 were firstly total synthesized. The syntheses of compounds 1, 5 and 6 were efficiently improved by the new synthetic routes. The structures of all synthetic compounds were confirmed by NMR, IR spectra and MS.