Efficient Synthesis of 6-O-methyl-scutellarein from Scutellarin via Selective Methylation

Scutellarin (1) possesses distinguished efficacy in the clinical therapy of cerebral infarction, coronary heart disease, and angina pectoris. Scutellarin (1) is readily converted in vivo, therefore, synthetic methods for the construction of its metabolites will be very important in the near future. In this work, an efficient and first synthetic method for 6-O-methyl-scutellarein (3), one metabolite of scutellarin in vivo, is developed. Dichlorodiphenylmethane in diphenyl ether is used firstly to protect the dihydroxy groups at C-6 and C-7 in scutellarein (2). Then, benzyl bromide is used to selectively protect the hydroxy groups at C-4' and C-7 in 10. 6-O-Methyl-scutellarein (3) is obtained in high yield through seven steps.