Selective synthesis of allylated oxime ethers and nitrones based on palladium-catalyzed allylic substitution of oximes.
Selective synthesis of allylated oxime ethers and nitrones based on palladium-catalyzed allylic substitution of oximes.
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DOI：
10.1021/jo050632
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发表时间：
2005-06
期刊：
影响因子：
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通讯作者：
H. Miyabe;Kazumasa Yoshida;V. K. Reddy;A. Matsumura;Y. Takemoto
中科院分区：
文献类型：
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作者：
H. Miyabe;Kazumasa Yoshida;V. K. Reddy;A. Matsumura;Y. Takemoto
[反应：见正文]考查了在过渡金属催化的烯丙基取代反应中作为亲核试剂的肟类化合物的生存能力。在pi-烯丙基钯配合物的反应中，肟的氧原子起到了活性亲核剂的作用。在Pd(PPh_3)_4存在下，由烯丙基碳酸酯与肟基进行烯丙基取代得到了不含碱的O-烯丙基线性肟醚。相反，在K2CO3或Et2Zn存在下，钯催化的与乙酸烯丙酯的反应进展顺利。用钯(II)催化剂实现了硝酮的选择性生成。在Pd(CoD)Cl2存在下，在无溶剂的条件下，由酮与烯丙基乙酸烯丙基取代生成N-烯丙基硝酮，这是与肟的氮原子反应的结果。
[reaction: see text] The viability of oximes as nucleophiles in transition-metal-catalyzed allylic substitution was examined. The oxygen atom of oxime acted as a reactive nucleophile in the reaction of a pi-allyl palladium complex. In the presence of Pd(PPh3)4, the allylic substitution of oximes with allylic carbonate afforded the linear O-allylated oxime ethers selectively without a base. In contrast, the palladium-catalyzed reaction with allylic acetate proceeded smoothly in the presence of K2CO3 or Et2Zn as a base. Selective formation of nitrones was achieved by using palladium(II) catalyst. In the presence of Pd(cod)Cl2, the allylic substitution of oximes with allylic acetate afforded the N-allylated nitrones under solvent-free conditions, as a result of the reaction with the nitrogen atom of oximes.