Chiral oxime ethers in asymmetric synthesis. Part 5. - Asymmetric synthesis of 2-substituted 5-to 8-membered nitrogen heterocycles by oxime addition-ring-closing metathesis
Chiral oxime ethers in asymmetric synthesis. Part 5. - Asymmetric synthesis of 2-substituted 5-to 8-membered nitrogen heterocycles by oxime addition-ring-closing metathesis
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DOI：
10.1039/b207235c
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发表时间：
2002-01-01
期刊：
影响因子：
--
通讯作者：
Moody, CJ
中科院分区：
文献类型：
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作者：
Hunt, JCA;Laurent, P;Moody, CJ
将有机金属试剂加成到衍生自不饱和醛的手性肟醚1上，或将含烯烃的有机金属加成到手性醛肟醚2上，导致高度立体选择性地形成羟胺6。N-烯丙基化得到二烯7，其经历闭环复分解（RCM）反应得到5-、6-和7-元氮杂环8。同样，也通过与肟醚的立体选择性加成制备的氨基甲酸苄酯9转化为二烯10，其进行RCM得到5-至8-元氮杂环11。因此，肟加成-RCM方案是不对称合成氮杂环的通用方法，进一步通过将不饱和杂环转化为手性哌啶，包括生物碱（-）-毒芹碱来举例说明。
Addition of organometallic reagents to chiral oxime ethers 1 derived from an unsaturated aldehyde, or addition of an alkene containing organometallic to chiral aldoxime ethers 2 results in highly stereoselective formation of the hydroxylamines 6. N-Allylation gives the dienes 7 which undergo ring-closing metathesis (RCM) reaction to give the 5-, 6-, and 7-membered nitrogen heterocycles 8. Likewise, the benzyl carbamates 9, also prepared by stereoselective addition to oxime ethers, were converted into dienes 10, which underwent RCM to give the 5- to 8-membered azacycles 11. The oxime addition-RCM protocol is thus a versatile method for the asymmetric synthesis of nitrogen heterocycles, further exemplified by the conversion of the unsaturated heterocycles into chiral piperidines, including the alkaloid (-)-coniine.