A SHORT ENANTIOSPECIFIC SYNTHESIS OF THE CEROPLASTIN NUCLEUS
A SHORT ENANTIOSPECIFIC SYNTHESIS OF THE CEROPLASTIN NUCLEUS
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DOI：
10.1021/jo00039a021
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发表时间：
1992-06-19
影响因子：
3.6
通讯作者：
YANG, K
中科院分区：
文献类型：
--
作者：
SNIDER, BB;YANG, K
以1-环戊烯甲醛为起始原料，经10步反应，立体选择性地合成了蜡塑素I和蜡塑酸的三环核9 b。将（3-甲基-3-丁烯基）溴化镁加到亚胺13 b上，用甲基碘通过古贺的方法甲基化，得到94%的光学纯醛40，如前面在我们的reiswigin A合成中所述。醛40的双键与HI异构化得到醛17 b。由甲硅烷基烯醇醚45制备的烯醇化物与醛17 b的偶联仅在三个步骤中得到46 a和46 b的1：1混合物，其含有9 b的完整碳骨架。脱水得到烯酮47 a和47 b。用Li/NH3还原47 a和47 b得到饱和酮48 at和48 bt，用LiAlH 4还原得到饱和醇49 att和49 btt。保护作为TBDMS醚的醇和氧化裂解二烯得到容易分离的酮醛51和56。51的McMurry偶联、甲硅烷基醚的裂解和用PCC氧化醇完成了9 b的合成。
The tricyclic nucleus 9b of ceroplastol I and ceroplasteric acid has been synthesized stereoselectively and enantiospecifically in only 10 steps from 1-cyclopentenecarboxaldehyde. Addition of (3-methyl-3-butenyl)magnesium bromide to imine 13b and methylation with methyl iodide by Koga's procedure gave 94% of optically pure aldehyde 40 as previously described in our reiswigin A synthesis. Isomerization of the double bond of aldehyde 40 with HI afforded aldehyde 17b. Coupling of the enolate prepared from silyl enol ether 45 with aldehyde 17b gave a 1:1 mixture of 46a and 46b, which contain the complete carbon skeleton of 9b, in only three steps. Dehydration provided enones 47a and 47b. Reduction of 47a and 47b with Li/NH3 afforded saturated ketones 48at and 48bt that were reduced with LiAlH4 to the saturated alcohols 49att and 49btt. Protection of the alcohols as the TBDMS ethers and oxidative cleavage of the dienes afforded readily separable keto aldehydes 51 and 56. McMurry coupling of 51, cleavage of the silyl ether, and oxidation of the alcohol with PCC completed the synthesis of 9b.