Abstract Total synthesis of biologically interesting natural and unnatural pyranoflavones has been accomplished starting from readily available 2, 4-dihydroxyacetophenone or 2, 4- dihydroxy-6-methoxyacetophenone in three steps, ie, benzopyran formation, condensation,
![5-Methoxy-2-phenyl-8,8-dimethyl-4H,8H-benzo[1,2-b:3,4-b']dipyran-4-one结构式](https://image.chemsrc.com/caspic/089/64125-33-3.png)