State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000, China.
Department of Chemistry and Centre for Scientific Modeling and Computation, Chinese University of Hong Kong, Shatin, Hong Kong, China.
J Am Chem Soc. 2021 May 26;143(20):7868-7875. doi: 10.1021/jacs.1c04114. Epub 2021 May 11.
The first synthesis of highly strained spirocyclobutane-pyrrolines via a palladium-catalyzed tandem Narasaka-Heck/C(sp or sp)-H activation reaction is reported here. The key step in this transformation is the activation of a δ-C-H bond via an in situ generated σ-alkyl-Pd(II) species to form a five-membered spiro-palladacycle intermediate. The concerted metalation-deprotonation (CMD) process, rate-determining step, and energy barrier of the entire reaction were explored by density functional theory (DFT) calculations. Moreover, a series of control experiments was conducted to probe the rate-determining step and reversibility of the C(sp)-H activation step.
本文报道了首例通过钯催化的串联 Narasaka-Heck/C(sp 或 sp)-H 活化反应合成高度应变的螺环丁烷-吡咯啉。此转化中的关键步骤是通过原位生成的σ-烷基-Pd(II)物种活化δ-C-H 键，形成五元螺钯环中间体。通过密度泛函理论（DFT）计算，研究了协同金属化-去质子化（CMD）过程、整个反应的速率决定步骤和能垒。此外，还进行了一系列对照实验，以探究 C(sp)-H 活化步骤的速率决定步骤和可逆性。
