BIOMIMETIC SYNTHESIS OF THE PENTACYCLIC NUCLEUS OF PTILOMYCALIN-A
BIOMIMETIC SYNTHESIS OF THE PENTACYCLIC NUCLEUS OF PTILOMYCALIN-A
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DOI：
10.1021/ja00081a015
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发表时间：
1994-01-26
影响因子：
15
通讯作者：
SHI, ZP
中科院分区：
文献类型：
--
作者：
SNIDER, BB;SHI, ZP
Ptilomycalin A（9）的五环核的甲酯已经通过有效的、收敛的、生物遗传的14步路线制备。关键步骤包括在四个步骤中将无环双烯酮39转化为9。O-甲基异脲与39的Michael加成得到52%的异脲40和41的混合物，它们都通过氨解转化为72%的三环缩胺42和43。用HF将甲硅烷基醚脱保护并用Et 3 N在MeOH中环化，得到9（从42几乎等于34%）和具有平伏甲酯基团的非对映异构体45（从42几乎等于26%）。
The methyl ester of the pentacyclic nucleus of ptilomycalin A (9) has been prepared by an efficient, convergent, biogenetic, 14-step route. The key steps involve the conversion of acyclic bis enone 39 to 9 in four steps. Michael addition of O-methylisourea to 39 afforded 52% of a mixture of isoureas 40 and 41, which were both converted to 72% of tricyclic aminals 42 and 43 by ammonolysis. Deprotection of the silyl ethers with HF and cyclization with Et3N in MeOH afforded 9 (almost-equal-to 34% from 42) and the diastereomer 45 with an equatorial methyl ester group (almost-equal-to 26% from 42).