γ-pyrone化合物. 3. Norathyriol衍生物的合成與抗血小板活性

γ-Pyrone Compounds. 3. Synthesis and Antiplatelet Effects of Norathyriol Derivatives

Norathyriol與各種acidic anhydride和acyl chloride酯化形成六種norathyriol酯類，以適當原料經由Friedel-Crafts acylation所產生之benzophenone precursor，再經鹽基催化，脫除甲醇，進行環化可合成得norathyriol tetramethyl ether. Norathyriol tetramethyl ether與BCl3進行選擇性demethylation反應而可合成得2,4-di-C-prenyl-1-hydroxy-3, 6, 7-trimethoxyxanthone，本實驗結果顯示norathyriol衍生物之抗血小板活性以norathyriol tetrapropionate與norathyriol tetracrotonate最強，其次是norathyriol tetracinnamate 及norathyriol tetramethyl ether。

Six norathyriol esters have been synthesized from various acidic anhydride and acyl chloride. Norathyriol tetramethyl ether was synthesized from benzophenone precursor by Friedel-Crafts acylation, and subsequently base-catalyzed cyclization to eliminate methanol. Selective demethylation of norathyriol tetramethyl ether with boron trichloride gave l-hydroxy-3, 6, 7-trimethoxyxanthone and then reacted with prenyl bromide to give 2, 4-di-C-prenyl-1-hydroxy-3, 6, 7-trimethoxyxanthone. According to the results of this study, norathyriol tetrapropionate and norathyriol tetracrotonate are the most potent antiplatelet compound, and the norathyriol tetracinnamate and norathyriol tetramethyl ether showed significant antiplatelet effects.