Figure 1. Synthesis of 5,3’,4’-trimethoxyflavone (6j) and 5,3’,4’-trihydroxyflavone (7j). i) Me2SO4, K2CO3, acetone, rt, 6h; ii) DCC, DMAP, 3,4-dimethoxybenzoic acid (3f); iii) KOH, pyridine, 100°C, 10 min; iv) 20% H2SO4/acetic acid, 100°C, 10 min; v) 1.0 M BBr3/CH2Cl2, rt, 12 h.