PENTACYCLIC TRITERPENE SYNTHESIS .5. SYNTHESIS OF OPTICALLY PURE RING AB PRECURSORS
PENTACYCLIC TRITERPENE SYNTHESIS .5. SYNTHESIS OF OPTICALLY PURE RING AB PRECURSORS
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DOI：
10.1021/jo00878a001
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发表时间：
1976-01-01
影响因子：
3.6
通讯作者：
HEATHCOCK, CH
中科院分区：
文献类型：
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作者：
DUTCHER, JS;MACMILLAN, JG;HEATHCOCK, CH
双环烯酮5-亚甲基-1，1，4a β-三甲基-1，4，4a，5，8，8a α-六氢萘-2，6（3 H，7 H）-二酮2-（2，2-二甲基）三亚甲基缩酮（5），它是五环三萜的A环和B环的前体，从烯二酮（±）经10步合成。1，4a-二甲基-4，4a，7，8-四氢萘-2，5（3 H，6 H）-二酮，总收率16%。不饱和酮醇（.+-.）- 1，4a β-二甲基-5 β-羟基-4，4a，5，6，7，8-六氢萘-2（3 H）-酮拆分为对映异构体，并确定了其绝对立体结构。5的左旋对映体具有与五环三萜对应的绝对构型。
The bicyclic enone 5-methylene-1,1,4a.beta.-trimethyl-1,4,4a,5,8,8a.alpha.-hexahydronaphthalene-2,6(3H,7H)-dione 2-(2,2-aimethyl)trimethylene ketal (5), which is a precursor for rings A and B of the pentacyclic triterpenes, was synthesized in 10 steps from the enedione (.+-.)-1,4a-dimethyl-4,4a,7,8-tetrahydronaphthalene-2,5(3H,6H)-dione in 16% overall yield. Unsaturated keto alcohol (.+-.)-1,4a.beta.-dimethyl-5.beta.-hydroxy-4,4a,5,6,7,8-hexahydronaphthalene-2(3H)-one was resolved into its enantiomers and absolute stereostructures assigned. The levorotatory enantiomer of 5 has the absolute configuration corresponding to that of the pentacyclic triterpenes.