Reactive ketimino radical acceptors: intermolecular alkyl radical addition to imines with a phenolic hydroxyl group.
Reactive ketimino radical acceptors: intermolecular alkyl radical addition to imines with a phenolic hydroxyl group.
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DOI：
10.1021/jo052518x
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发表时间：
2006-01
期刊：
影响因子：
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通讯作者：
H. Miyabe;Y. Yamaoka;Y. Takemoto
中科院分区：
文献类型：
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作者：
H. Miyabe;Y. Yamaoka;Y. Takemoto
研究了氯胺酮碳氮双键的分子间碳自由基加成反应。在对各种醛二胺的反应性研究中，我们发现含有酚羟基的醛二胺7对亲核碳自由基表现出优异的反应性。酚羟基的一个显著作用被认为是由羟基提供的中间氨基自由基的稳定。活性酮胺酮受体的筛选表明，具有酚羟基的酮胺酮15、酮胺酮17和酮胺酮19具有良好的反应活性。酮胺15、17和19的自由基加成是在亚胺碳上选择性地发生的，得到了c -烷基化产物，而没有形成n -烷基化产物。用手性盒子配体和Zn(OTf)2对映选择性乙基加成氯胺酮15，在80% ee下得到二乙基化产物30。
Intermolecular carbon radical addition to the carbon-nitrogen double bond of ketimines was studied. In the study on the reactivity of various aldimines, we found that the aldimine 7 having a phenolic hydroxyl group shows an excellent reactivity toward nucleophilic carbon radicals. A remarkable effect of phenolic hydroxyl group is assumed to be the stabilization of intermediate aminyl radical provided by a hydroxyl group. The screening of reactive ketimino acceptors showed that ketimines 15, 17, and 19 having a phenolic hydroxyl group exhibit excellent reactivities. The radical addition to ketimines 15, 17, and 19 took place regioselectively at the imino carbon to give the C-alkylated products without the formation of N-alkylated products. Enantioselective ethyl radical addition to ketimine 15 using chiral box ligand and Zn(OTf)2 gave the diethylated product 30 in 80% ee.