General, robust, and stereocomplementary preparation of β-ketoester enol tosylates as cross-coupling partners utilizing TsCl-N-methylimidazole agents
General, robust, and stereocomplementary preparation of β-ketoester enol tosylates as cross-coupling partners utilizing TsCl-N-methylimidazole agents
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DOI：
10.1021/ol800480d
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发表时间：
2008-06-05
期刊：
影响因子：
5.2
通讯作者：
Tanabe, Yoo
中科院分区：
文献类型：
--
作者：
Nakatsuji, Hidefumi;Ueno, Kanako;Tanabe, Yoo
We have developed a general, robust, and cost-effective method for the (E)- or (2)-stereocomplementary enol tosylation of ss-ketoesters using TsCl-N-methylimidazole (NMI)-Et3N or LiOH. TsCl coupled with NMI formed a highly reactive N-sulfonylammonium intermediate. Stereocongested secondary alcohols were smoothly sulfonylated using Ts(Ms)Cl-NMI-Et3N. ss-Ketoesters underwent (E)-selective tosylation using TsCl-NMI-Et3N and (2)-selective tosylation using TsCl-NMI-LiOH (total of 23 examples; 60%-99% yield). Stereoretentive Negishi and Sonogashira couplings using enol tosylates proceeded successfully to give trisubstituted alpha, beta-unsaturated esters.
