Base-induced sequential cyclization-rearrangement of enantioenriched 3-aminoalkanoates to five- and seven-membered lactams.
Base-induced sequential cyclization-rearrangement of enantioenriched 3-aminoalkanoates to five- and seven-membered lactams.
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DOI：
10.1002/asia.200700423
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发表时间：
2008-09
期刊：
影响因子：
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通讯作者：
Takeo Sakai;Ken‐ichi Yamada;K. Tomioka
中科院分区：
文献类型：
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作者：
Takeo Sakai;Ken‐ichi Yamada;K. Tomioka
通过用tBuLi处理，线性3-氨基烷酸酯（4）立体选择性地转化为五元和七元内酰胺（反式-5和顺式-6）。从4到5和6，最初环化为氮杂环丁烷-2-酮以及随后的氮杂-[1，2]和[2，3]重排是可能的机理途径。尽管对映体富集的4被转化为几乎外消旋的5和6，但在酯α位具有90%ee手性的线性3-氨基-2-甲基链烷酸酯（17）得到了具有三个不对称中心的全顺式七元内酰胺（18），具有85%ee。
By treatment with tBuLi, linear 3-aminoalkanoates (4) were converted stereoselectively into five- and seven-membered lactams (trans-5 and cis-6). Initial cyclization to azetidin-2-one with subsequent aza-[1,2] and [2,3] rearrangement is the probable mechanistic pathway from 4 to 5 and 6. Although enantioenriched 4 was converted into nearly racemic 5 and 6, a linear 3-amino-2-methylalkanoate (17) with 90 % ee bearing chirality at the ester alpha-position afforded an all-cis seven-membered lactam (18) bearing three asymmetric centers with 85 % ee.