Electrophilic Activation of Iodonium Ylides by Halogen-Bond-Donor Catalysis for Cross-Enolate Coupling.
Electrophilic Activation of Iodonium Ylides by Halogen-Bond-Donor Catalysis for Cross-Enolate Coupling.
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DOI：
10.1002/anie.201703641
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发表时间：
2017-06
影响因子：
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通讯作者：
M. Saito;Yusuke Kobayashi;S. Tsuzuki;Y. Takemoto
中科院分区：
文献类型：
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作者：
M. Saito;Yusuke Kobayashi;S. Tsuzuki;Y. Takemoto
甲硅烷基烯醇醚与碘鎓(III)叶立德的反极性烷基化反应在温和条件下进行，在卤素键合催化剂存在下以高收率得到各种1,4-二羰基化合物。与此类叶立德前体的典型过渡金属活化过程（往往通过类胡萝卜素中间体进行）不同，实验和计算研究表明，XB供体催化剂和碘鎓叶立德之间的卤素键（XB）在促进反应中起着至关重要的作用。相容的布朗斯台德碱催化剂的鉴定使得该方法能够扩展到原位生成的烯醇，从而以良好的收率得到相应的加合物。
The umpolung alkylation of silyl enol ethers with an iodonium(III) ylide proceeds under mild conditions to afford various 1,4-dicarbonyl compounds in high yields in the presence of a halogen-bonding catalyst. Unlike typical transition-metal activation processes of such ylide precursors, which tend to proceed via carbenoid intermediates, experimental and computational studies indicate that halogen bonding (XB) between the XB donor catalyst and the iodonium ylide plays a crucial role in promoting the reaction. The identification of a compatible Bronsted base catalyst enabled the extension of this method to enols generated in situ to give the corresponding adducts in good yields.