2.Synthesis of Multisubstituted Silyloxy-based Donor-Acceptor Cyclobutanes by an Acid-Catalyzed [2+2] Cycloaddition
2.Synthesis of Multisubstituted Silyloxy-based Donor-Acceptor Cyclobutanes by an Acid-Catalyzed [2+2] Cycloaddition
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2.酸催化[2 2]环加成合成多取代甲硅烷氧基供体-受体环丁烷
DOI：
10.1002/ijch.201500096
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
K.
中科院分区：
文献类型：
--
作者：
Takasu;K.
本文总结了我们最近在酸催化的烯醇醚与α，β-不饱和酯的[2+2]环加成反应中所做的工作，得到了给体-受体（D-A）环丁烷及其相关反应。环加成通常以良好的产率和高的非对映选择性产生多取代的环丁烷。发现铝刘易斯酸和三氟甲磺酸酰亚胺（Tf_2NH）具有较好的催化活性。逆[2+2]环加成反应在较高的反应温度下进行，在某些情况下，观察到环加成物的非对映选择性切换。建立了Tf 2NH-催化的[2+2]环加成反应的微流方案。虽然环加成反应通常需要在间歇反应器中的低温条件下进行，但微反应器系统即使在环境温度下也能够生产D-A环丁烷。[2+2]烯丙基硅烷与烯醇醚取代烯醇醚环加成得到相应的D-A环丁烷。
This account summarizes our recent efforts on the acid‐catalyzed [2+2] cycloaddition of silyl enol ethers with α,β‐unsaturated esters, giving donor‐acceptor (D‐A) cyclobutanes and their related reactions. The cycloaddition generally produces multisubstituted cyclobutanes in good yields with high diastereoselectivity. We found that aluminum Lewis acids and triflic imide (Tf2NH) had good catalytic activity. The retro [2+2] cycloaddition proceeded at higher reaction temperatures, and in some cases, diastereoselectivity switching of cycloadducts was observed. A microflow protocol was established for Tf2NH‐catalyzed [2+2] cycloaddition. Although the cycloaddition usually requires cryogenic conditions in a batch reactor, the microreactor system enabled the production ofD‐A cyclobutanes, even at ambient temperature. [2+2] Cycloaddition of allylsilanes and alkyl enol ethers, instead of silyl enol ethers, afforded the correspondingD‐A cyclobutanes.