Fujii Takuji, Wang Qian, Zhu Jieping
Laboratory of Synthesis and Natural Products (LSPN), Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne, EPFL-SB-ISIC-LSPN, BCH, 5304, 1015, Lausanne, Switzerland.
Angew Chem Int Ed Engl. 2024 May 27;63(22):e202403484. doi: 10.1002/anie.202403484. Epub 2024 Apr 12.
In contrast to the well-studied 1-vinylcyclobutanols, the reactivity of 3-vinylazetidin-3-ols 1 and 3-vinyloxetan-3-ols 2 under transition metal catalysis remains largely unexplored. We report herein their unique reactivity under dual palladium and acid catalysis. In the presence of a catalytic amount of Pd(OAc)(PPh), AgTFA and triflic acid, the reaction of 1 or 2 with aryl iodides affords 2,3,4-trisubstituted dihydrofurans, which are valuable heterocycles in organic synthesis. Mechanistic studies reveal that this arylative ring-expansion reaction proceeds via a domino process involving Heck arylation of alkene, acid-catalyzed transposition of allylic alcohol and ring opening of the azetidine/oxetane by an internal hydroxyl group.
与已得到充分研究的1-乙烯基环丁醇不同，3-乙烯基氮杂环丁烷-3-醇1和3-乙烯基氧杂环丁烷-3-醇2在过渡金属催化下的反应性在很大程度上仍未被探索。我们在此报告它们在钯和酸双催化下的独特反应性。在催化量的Pd(OAc)(PPh)、AgTFA和三氟甲磺酸存在下，1或2与芳基碘反应生成2,3,4-三取代二氢呋喃，这些是有机合成中有价值的杂环化合物。机理研究表明，这种芳基化扩环反应通过一个多米诺过程进行，该过程涉及烯烃的Heck芳基化、酸催化的烯丙醇重排以及氮杂环丁烷/氧杂环丁烷被内部羟基开环。
