Stereochemistry and reactions of presilphiperfolanol: A branch point marker in triquinane sesquiterpene biogenesis
Stereochemistry and reactions of presilphiperfolanol: A branch point marker in triquinane sesquiterpene biogenesis
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DOI：
10.1021/ja961582g
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发表时间：
1996-10-02
影响因子：
15
通讯作者：
Wilson, SR
中科院分区：
文献类型：
--
作者：
Coates, RM;Ho, ZQ;Wilson, SR
三环倍半萜醇(-)-预苯四烯醇是角型和螺旋型三醌倍半萜烯的结构前体，其结构和立体化学性质确定为(1S,4S,7S,8S,11S)-2,2,4,8-四甲基三环[5.3.1.0(4,11)]十一烷-11-醇[[2aS-(2a α,4a β,5 β,7a β,7b β)]-十氢-1,1,2a，5-四甲基- 7h -环戊烷[cd] -7b-ol，[1]通过对其对硝基苯甲酸衍生物8a的x射线晶体学分析以及与(-)-硅油酚-6-烯(6)的相关性。1的脱水产生2:1的pre - ilphiperfol1(8)-和7-enes（9 + 10）混合物，它们在α和β面上都进行了环氧化反应，酸催化的h2so4 -硅胶脱水导致通过迁移i来竞争环收缩。C11和C9与C8以98:1的比例生成硅油烯(6)和-terrecyclene（12）。8a在60%的丙酮水溶液中溶解，得到烯烃（9 + 10 + 6）和1（9%）的混合物作为唯一的醇产物。反式双环[3,3,0]辛烷-1-基对硝基苯甲酸酯的溶解速率(50℃时为5.2 × 10（-5) s(-1)）与文献值的相似性表明，在各自的过渡态中，应变缓解水平相当。
The structure and stereochemistry of the tricyclic sesquiterpene alcohol (-)-presilphiperfolanol, a structural precursor for the angular and propellane triquinane sesquiterpenes, are established as (1S,4S,7S,8S,11S)-2,2,4,8-tetramethyltricyclo[5.3.1.0(4,11)] undecan-11-ol [[2aS-(2a alpha,4a beta,5 beta,7a beta,7b beta)]-decahydro-1,1,2a,5-tetramethyl-7bH-cyclopenta[cd]inden-7b-ol, 1] by an X-ray crystallographic analysis of its p-nitrobenzoate derivative 8a and by correlation with (-)-silphiperfol-6-ene (6). Dehydration of 1 afforded a 2:1 mixture of presilphiperfol-1(8)- and 7-enes (9 + 10) which underwent epoxidation on both alpha and beta faces, Acid-catalyzed dehydration with H2SO4-silica gel lead to competing ring contractions by migrations oi. C11 and C9 to C8 la give silphiperfolene (6) and alpha-terrecyclene (12) in a 98:1 ratio. Solvolysis of 8a in 60% aqueous acetone provided a mixture of olefins (9 + 10 + 6) and 1 (9%) as the sole alcohol product. The similarity of the solvolysis rate (5.2 x 10(-5) s(-1) at 50 degrees C) to the literature value for trans-bicyclo[3,3,0]octan-1-yl p-nitrobenzoate indicates comparable levels of strain relief in the respective transition states.