Functionalization of<i>trans</i>-Decalin. III. A Stereospecific Preparation of Vicinal<i>cis</i>Two Methyl Groups of Eremophilane Skeleton, Leading to<i>dl</i>-Dehydrofukinone
作者:Sigeru Torii、Tsutomu Inokuchi、Tetsuo Yamafuji
DOI:10.1246/bcsj.52.2640
日期:1979.9
A procedure for the preparation of dl-dehydrofukinone (1), an eremophilane type sesquiterpene, from the diene adducts (3), prepared from the reaction of 4-methyl-3-methoxycarbonyl-2-cyclohexen-1-one with butadiene, is described. Acetalization-reduction (LiAlH4) of 3 followed by treatment of the corresponding mesylate with base provided 5,6-cis-5-methyltricyclo[4.4.1.01,6]undec-8-en-2-one (7) in 69% overall yields. Reductive cleavage of 7 with lithium metal afforded trans-4β,4aβ-dimethyl-Δ6,7-octalin-1-one (8), bearing a set of vicinal cis two methyl groups on the C-4 and C-4a carbons in an 83% yield. Functionalization of the double bond of 8 involves (1) reduction of carbonyl group and following tetrahydropyranylation, (2) epoxidation followed by regiospecific reduction of the oxirane ring at the C-6 position, and (3) subsequent oxidation of the hydroxyl group, giving trans-4aβ,5β-dimethyl-8β-tetrahydropyranyloxydecalin-2-one (14b) in good yields. The conversion of 14b into the desired 1 was achieved smoothly by (1) hydrolysis of tetrahydropyranyl ether, (2) pyrolysis of its mesylate, and (3) subsequent aldol reaction with acetone followed with dehydration and isomerization of the double bond.
本文描述了一种从 4-甲基-3-甲氧羰基-2-环己烯-1-酮与丁二烯反应制备的二烯加合物(3)中制备 dl-脱氢紫杉酮(1)(一种 eremophilane 型倍半萜)的方法。先对 3 进行乙缩醛化还原(LiAlH4),然后用碱处理相应的甲磺酸盐,最后得到 5,6-顺式-5-甲基三环[4.4.1.01,6]十一碳-8-烯-2-酮(7),总产率为 69%。用金属锂对 7 进行还原裂解,得到了反式-4β,4aβ-二甲基-Δ6,7-辛烯-1-酮(8),该化合物在 C-4 和 C-4a 碳上带有一组邻接的顺式两个甲基,收率为 83%。8 双键的官能化过程包括:(1) 还原羰基,然后进行四氢吡喃化;(2) 环氧化,然后在 C-6 位进行环氧乙烷环的区域特异性还原;(3) 随后氧化羟基,得到反式-4aβ,5β-二甲基-8β-四氢吡喃氧基萘-2-酮(14b),收率很高。通过 (1) 四氢吡喃基醚的水解,(2) 其甲磺酸盐的热解,(3) 随后与丙酮的醛醇反应,以及双键的脱水和异构化,可以顺利地将 14b 转化为所需的 1。