Abstract Baicalein, an important active constituent of the traditional Chinese herb Scutellaria baicalensis, exhibited antitumor activity and inhibitory activity against P-gp 170. The syntheses of 25 baicalein derivatives, 2–26 (Table), are described here (Scheme 1). These compounds were systematically modified with O-alkylation and O-acylation at HO [BOND] C (5), HO [BOND] C (6), and HO [BOND] C (7), singly or in combination, on the ring A of ...