Synthesis of 6-Methoxy-1,1,10-trimethyl-1,2,3,4-tetrahydroanthracene, a Synthetic Intermediate of a Linear Abietane Diterpene, Umbrosone.
作者:Takashi MATSUMOTO、Yoshio TAKEDA、Shuji USUI、Sachihiko IMAI
DOI:10.1248/cpb.44.530
日期:——
Methyl 13-acetyl-12-methoxy-8, 11, 13-podocarpatrien-18-oate, prepared from (+)-dehydroabietic acid, was converted into methyl 12-methoxy-7-oxo-5, 8, 11, 13-podocarpatetraen-18-oate (9) by a series of reactions : haloform reaction, decarboxylation, Jones oxidation, and dehydrogenation. Reduction of 9 with sodium borohydride, followed by treatment of the resulting 7-hydroxy compound with boron trifluoride etherate, afforded a rearranged ester, methyl 6-methoxy-1, 10-dimethyl-1, 2, 3, 4-tetrahydroanthracene-1-carboxylate. This was further converted into 6-methoxy-1, 1, 10-trimethyl-1, 2, 3, 4-tetrahydroanthracene (14) by means of the following reactions : lithium aluminum hydride reduction, pyridinium chlorochromate oxidation, and Huang-Minlon reduction. Compound 14 was finally converted into the desired orthoquinone (1) according to the procedure of Ghosh and Ghatak. The synthetic 1 was shown to be identical with natural umbrosone by spectral comparisons.
将由 (+)-脱氢松香酸制备的 13-乙酰基-12-甲氧基-8, 11, 13-podocarpatrien-18-oate 甲酯转化为 12-甲氧基-7-氧代-5, 8, 11, 13-甲酯podocarpatetraen-18-oate (9)经一系列反应:卤仿反应、脱羧、琼斯氧化、脱氢。用硼氢化钠还原9,然后用乙醚三氟化硼处理所得7-羟基化合物,得到重排酯,甲基6-甲氧基-1,10-二甲基-1,2,3,4-四氢蒽-1-羧酸盐。通过氢化铝锂还原、氯铬酸吡啶鎓氧化和黄敏隆还原反应进一步转化为6-甲氧基-1,1,10-三甲基-1,2,3,4-四氢蒽(14) 。根据Ghosh和Ghatak的方法,化合物14最终转化为所需的邻醌(1)。通过光谱比较表明合成的 1 与天然 umbrosone 相同。