Yu Ziqi, Shi Min, Wei Yin
Key Laboratory for Advanced Materials, Institute of Fine Chemicals, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Meilong Road No. 130, Shanghai 200237, China.
State Key Laboratory of Organometallic Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China.
Molecules. 2024 Feb 29;29(5):1085. doi: 10.3390/molecules29051085.
Rhodium-catalyzed cycloaddition reactions are a powerful tool for the construction of polycyclic compounds. Combined experimental and DFT studies were used to investigate the temperature-controlled chemoselectivity of cationic rhodium-catalyzed intramolecular cycloaddition reactions of ene-vinylidenecyclopropanes. After a series of mechanistic studies, it was found that trace amounts of water in the reaction system play an important role in generating the product with double bond located on a five-membered ring and revealed that trace amounts of water in the reaction system, including the rhodium catalyst, substrate and solvent, were sufficient to promote the formation of the product with double bond located on a five-membered ring, and additional water could not further accelerate the reaction. DFT calculation results show that the addition of water indeed significantly lowers the energy barrier of the proton transfer step, making the formation of the product with double bond located on a five-membered ring more likely to occur and confirming the rationality of water-assisted proton transfer occurring in the selective access to the product with double bond located on a five-membered ring.
铑催化的环加成反应是构建多环化合物的有力工具。结合实验和密度泛函理论（DFT）研究，对阳离子铑催化的烯基-亚乙烯基环丙烷分子内环加成反应的温度控制化学选择性进行了研究。经过一系列机理研究，发现反应体系中的痕量水在生成双键位于五元环上的产物中起着重要作用，并且表明反应体系中的痕量水，包括铑催化剂、底物和溶剂，足以促进双键位于五元环上的产物的形成，额外的水并不能进一步加速反应。DFT计算结果表明，水的加入确实显著降低了质子转移步骤的能垒，使得双键位于五元环上的产物更易形成，并证实了在选择性生成双键位于五元环上的产物过程中发生水辅助质子转移的合理性。
