TfOH- and HBF4-Mediated Formal Cycloisomerizations and [4+3] Cycloadditions of Allene-alkynylbenzenes
TfOH- and HBF4-Mediated Formal Cycloisomerizations and [4+3] Cycloadditions of Allene-alkynylbenzenes
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TfOH-和HBF4-介导的丙二烯-炔基苯的形式环异构化和[4 3]环加成
DOI：
10.1021/acs.joc.8b00393
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发表时间：
2018
影响因子：
3.6
通讯作者：
Yu Zhi-Xiang
中科院分区：
文献类型：
--
作者：
Xiang Yu;Li Zining;Wang Lu-Ning;Yu Zhi-Xiang
研究了一种无金属、TfOH（1.1当量）介导的易制备的烯基炔基苯的形式环异构化反应，得到吡咯烷和环戊烷衍生物。该反应首先由烯丙烯生成烯丙基阳离子，随后炔与烯丙基阳离子反应生成乙烯基阳离子，最后被三氟酸盐（TfO）阴离子截获。通过使用10等量的TfOH，这种环异构化可以进一步调整为酸介导的分子内形式[4+3]环加成（多余的酸被用来促进酸介导的环异构化产物的Friedel-Crafts反应）。本体系也可应用于以hbf4或me3obf4为氟源合成含氟产品。
A metal-free, TfOH (1.1 equiv)-mediated formal cycloisomerization of easily prepared allene-alkynylbenzenes to give pyrrolidines and cyclopentanes derivatives was developed. This reaction is initiated by the generation of allylic cation from allene, followed by alkyne’s reaction with the allylic cation, to give a vinyl cation, which is finally intercepted by the triflate (TfO) anion. This cycloisomerization can be further tuned to become an acid-mediated intramolecular formal [4+3] cycloaddition by using 10 equiv of TfOH (The excess acid was used to promote the Friedel–Crafts reaction of the acid-mediated cycloisomerization products). The present system can also be applied to synthesized F-incorporated products by using HBF4or Me3OBF4as the fluoro source.