Improved,rapid andefficient synthesis of polymethoxyflavones under microwave irradiation and their inhibitory effects on melanogenesis

摘要

th emicrowave-assistedmehtylation of 2,5-dihydroxy-1,3-dimethoxybenzene with(CH_3O)_2SO_2 for 5 min gave easily 1,2,3,5-tetrameethoxybenzene,which was converted intopentametoxybenzene.The microwave-assistedFriedel-Crafts acylation of pentametyoxybenzene in the presence of In(CF_3SO_3)_3 gave pentamethoxyacetophenone for 15 min under solvnet-free conditions in high yield.The microwave-assisted cyclization reactionof thediketones,whichwere synthesized fromthe acetophenone via three steps undermicrowave irradiation,gave thedesiredpolymethoxyflavones for 1.5-3 minin high yields.the polymethoxyflavones showed inhibitory effects on melanogenesis in a human melanoma.