Studies on the Chemical Constituents of the Plants of Coniferae and Allied Orders. XL

Decomposition of hinokiflavone pentamethyl ether with ethanolic potassium hydroxide produces anisic acid, p-methoxyacetophenone, 2-hydroxy-4, 6-dimethoxyacetophenone, a phenolic acid (Substance Y) of formula C17H16O7, and a phenolic diketone (Substance Z) of formula C18H18O6. Substances Y and Z were determined to have the respective structure of 2-hydroxy-3-acetyl-4, 6-dimethoxy-4′-carboxydiphenyl ether and 2-hydroxy-3, 4′-diacetyl-4, 6-dimethoxydiphenyl ether. All these substances, except 2-hydroxy-4, 6-dimethoxyacetophenone, originate from the ketoflavone structure, so that hinokiflavone should have one phloroglucinol system besides a ketoflavone. From these facts, it was concluded that hinokiflavone has a diphenyl ether-type bisflavonoid structure in which two moles of aplgenin are bonded in ether linkage at their 4′- and 8-position.