Efficient Chemical Synthesis of a Scutellarein Derivative Containing Morpholine Ring

Scutellarin (1) [5,6-dihydroxy-2-(4-hydroxyphenyl)-4-oxo-4H-1-benzopyran-7-yl β-D-glucopyranosiduronic acid] is very effective in the clinical treatment of cerebral infarction and coronary heart disease in China. Pharmacokinetic studies showed that scutellarin (1) is readily metabolized to scutellarein (2) [5,6,7-trihydroxy-2-(4-hydroxyphenyl)-4H-1- benzopyran-4-one] in the intestine by β-glucuronide enzyme prior to absorption. In order to improve the biological activity of scutellarin (1), our group has previously synthesized many scutellarin derivatives based on their in vivo metabolic mechanism. The results showed that morpholine ring substituted at C-7 or C-8 position induced better antioxidant activity, water solubility and anticoagulant activity compared to scutellarin (1). In this paper, an efficient synthetic method for the construction of 5,6,7-trihydroxy-2-[4-[2-(4-morpholinyl)ethoxy]phenyl]-4H-1-benzopyran-4-one (5) is reported. This synthetic route will facilitate the synthesis of scutellarein derivatives containing an amine side chain at the C- 4' position.