Synthesis of Pygmaeocine E, a Linear Abietane Diterpene from Pygmaeopremna herbacea (ROXB.) MOLDENKE.
作者:Takashi MATSUMOTO、Yoshio TAKEDA、Kimiko SOH、Hisashi GOTOH、Sachihiko IMAI
DOI:10.1248/cpb.44.1318
日期:——
Methyl 12-methoxy-7-oxo-8, 11, 13-abietatrien-18-oate (10), prepared from (+)-dehydroabietic acid (9), was rearranged into methyl 7-isopropyl-6-methoxy-1, 10-dimethyl-1, 2, 3, 4-tetrahydroanthracene-1-carboxylate (13) via a series of reaction : dehydrogenation with selenium(IV) oxide, sodium borohydrie reduction, and dehydration with boron trifluoride etherate. Reduction of 13 with lithium aluminum hydride afforded an alcohol (14), which was further reaffanged into 2-isopropyl-3-methoxy-5, 9-dimethyl-7, 8-dihydro-6H-cyclohepta[b]naphthalene (16) by treatment with methanesulfonyl chloride in pyridine. The alcohol 14 was then converted into 7-isopropyl-5, 6-dimethoxy-1, 1, 10-trimethyl-1, 2, 3, 4-tetrahydroanthracene (22) by means of the following reaction : pyridinium chlorochromate oxidation, Huang-Minlon reduction, demethylation, oxidation with Fremy's salt, catalytic hydrogenation, and methylation. Compound 22 was also prepared from methyl 11, 12-dimethoxy-7-oxo-8, 11, 13-abietatrien-18-oate (23) via methyl 7-isopropyl-5, 6-dimethoxy-1, 10-dimethyl-1, 2, 3, 4-tetrahydroanthracene-1-carboxylate (26). Treatment of 22 with DDQ produced an enone (29), which was converted into a diosphenol derivative (31) via a series of reaction : catalytic hydrogenation, and oxidations with Jones reagent and then with oxygen in the presence of potassium tert-butoxide. Demethylation of 31 with ethanethiol and anhydrous aluminum chloride afforded pygmaeocine E (1) and 3, 6-dihydroxy-7-isopropyl-1, 1, 10-trimethyl-1, 2-dihydroanthracen-2-one (32).
由(+)-脱氢松香酸(9)制备的 12-甲氧基-7-氧代-8,11,13-松香三烯-18-羧酸甲酯(10)通过一系列反应重新排列为 7-异丙基-6-甲氧基-1,10-二甲基-1,2,3,4-四氢蒽-1-羧酸甲酯(13):氧化硒(IV)脱氢、硼氢化钠还原和三氟化硼醚脱水。用氢化铝锂还原 13 后得到醇(14),在吡啶中用甲磺酰氯处理后,该醇进一步转化为 2-异丙基-3-甲氧基-5, 9-二甲基-7, 8-二氢-6H-环庚基[b]萘(16)。然后通过以下反应将醇 14 转化为 7-异丙基-5,6-二甲氧基-1,1,10-三甲基-1,2,3,4-四氢蒽 (22):氯铬酸吡啶鎓氧化、黄敏龙还原、脱甲基、弗莱米盐氧化、催化氢化和甲基化。化合物 22 也是通过 7-异丙基-5,6-二甲氧基-1,10-二甲基-1,2,3,4-四氢蒽-1-羧酸甲酯 (26) 从 11,12-二甲氧基-7-氧代-8,11,13-阿松三烯-18-酸甲酯 (23) 中制备出来的。用 DDQ 处理 22 会产生一种烯酮(29),通过一系列反应:催化加氢、用琼斯试剂氧化,然后在叔丁醇钾存在下用氧气氧化,该烯酮被转化成二苯酚衍生物(31)。用乙硫醇和无水氯化铝对 31 进行脱甲基反应,可得到吡蚜酮 E(1)和 3,6-二羟基-7-异丙基-1,1,10-三甲基-1,2-二氢蒽-2-酮(32)。