Pauson-Khand Reaction

The Pauson-Khand reaction is a [2+2+1] type cyclization reaction used to construct cyclopentenone moiety from alkynes and alkenes, mediated by dicobalt octacarbonyl. Alkynes have high affinity towards dicobalt octacarbonyl and form an alkyne-dicobalt intermediate which can be isolated. This intermediate then coordinates with an alkene followed by CO insertion to afford the cyclic product. In many cases, the Pauson-Khand reaction is utilized in the total synthesis of natural products bearing a cyclopentanone moiety.