"On-Droplet" Chemistry: The Cycloaddition of Diethyl Azodicarboxylate and Quadricyclane
"On-Droplet" Chemistry: The Cycloaddition of Diethyl Azodicarboxylate and Quadricyclane
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DOI：
10.1002/anie.201708413
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发表时间：
2017-11-20
影响因子：
16.6
通讯作者：
Zare, Richard N.
中科院分区：
文献类型：
--
作者：
Bain, Ryan M.;Sathyamoorthi, Shyam;Zare, Richard N.
Sharpless及其同事先前研究了偶氮二甲酸二乙酯（DEAD）和四环烷的[2 sigma + 2 sigma + 2 pi]环加成反应，并报告称向纯试剂中加入水会导致反应速率加快，从而产生所谓的水上化学。我们已经研究了相同的反应在水微滴（约。5m直径），并发现环加成反应比先前报道的“水上”反应更进一步加速（10（2）倍）。Sharpless及其同事在水以外的溶剂中证明的加速趋势在相应的微滴实验中得到了复制。我们还发现，DEAD与自身反应，形成各种肼羧酸盐，并在微滴中拦截该反应的中间体，以验证本文提出的机制。我们认为，“液滴上”化学反应，类似于“水上”化学反应，可能是一个具有合成意义的一般过程。
Sharpless and co-workers previously studied the [2 sigma + 2 sigma + 2 pi] cycloaddition of diethyl azodicarboxylate (DEAD) and quadricyclane and reported that the addition of water to the neat reagents caused an acceleration in the reaction rate, giving birth to what has been called on-water chemistry. We have examined the same reaction in aqueous microdroplets (ca. 5m diameter) and find that the cycloaddition reaction is accelerated even further (by a factor of 10(2)) compared to that of the "on-water" reaction reported previously. The trends of acceleration in solvents other than water demonstrated by Sharpless and colleagues were replicated in the corresponding microdroplet experiments. We also find that DEAD reacts with itself to form a variety of hydrazine carboxylates and intercept intermediates of this reaction in microdroplets to validate a mechanism proposed herein. We suggest that "on-droplet" chemistry, similar to "on-water" chemistry, may be a general process of synthetic interest.