What Controls Stereoselectivity and Reactivity in the Synthesis of a trans-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.