What Controls Stereoselectivity and Reactivity in the Synthesis of a <i>trans</i>-Decalin with a Quaternary Chiral Center via the Intramolecular Pauson–Khand Reaction: A Theoretical Study

The Co2(CO)8-mediated intramolecular Pauson–Khand reaction is an efficient approach to the trans-decalin subunit with a defined C1 quaternary chiral center. The newly developed density functional theory method M11-L was employed to study the mechanism, reactivity, and stereoselectivity for this reaction. The rate- and stereoselectivity-determining step is the intramolecular alkene insertion into the carbon–cobalt bond. Insertion of the alkene by the re- and si-face was studied to explain the stereoselectivity. The effects of varying the substituent on the acetylene and the C3 chirality were investigated experimentally and theoretically.以八羰基二钴（Co₂(CO)₈）介导的分子内帕克-坎德（Pauson-Khand）反应，是构建带有明确C1位手性季碳中心的反式十氢化萘结构单元的高效途径。本研究采用新近开发的M11-L密度泛函理论方法，对该反应的反应机理、反应活性及立体选择性展开了系统研究。该反应的速率与立体选择性决速步为烯烃分子内插入碳-钴键的过程。通过考察烯烃从re面与si面的插入路径，本研究阐释了该反应的立体选择性成因。此外，本研究通过实验与理论计算相结合的手段，探究了炔烃取代基以及C3位手性对反应的影响。