Transition‐Metal Catalysis of Triene 6π Electrocyclization: The π‐Complexation Strategy Realized

作者：Pengjin Qin, Lian Wang, J. M. O’Connor, Kim K. Baldridge, Yifan Li, Burak A. Tufekci, Jiyue Chen, Arnold L. Rheingold · 发表于：Angewandte Chemie International Edition · 年份：2020 · DOI：10.1002/anie.202006992 · 被引用次数：18 · 研究领域：Organometallic Complex Synthesis and Catalysis、Asymmetric Hydrogenation and Catalysis、Catalytic Alkyne Reactions

Abstract Triene 6π electrocyclization, wherein a conjugated triene undergoes a concerted stereospecific cycloisomerization to a cyclohexadiene, is a reaction of great historical and practical significance. In order to circumvent limitations imposed by the normally harsh reaction conditions, chemists have long sought to develop catalytic variants based upon the activating power of metal–alkene coordination. Herein, we demonstrate the first successful implementation of such a strategy by utilizing [(C 5 H 5 )Ru(NCMe) 3 ]PF 6 as a precatalyst for the disrotatory 6π electrocyclization of highly substituted trienes that are resistant to thermal cyclization. Mechanistic and computational studies implicate hexahapto transition‐metal coordination as responsible for lowering the energetic barrier to ring closure. This work establishes a foundation for the development of new catalysts for stereoselective electrocyclizations.