2‐Pentylcyclopent‐2‐en‐1‐one by Catalytic Pauson‐Khand Reaction

Abstract

Only 0.0022 mole equivalents of the catalyst [Co2(CO)8] are necessary for the preparation of the cyclopentenone 1 from 1-heptyne, ethylene, and CO with an exchange number of about 220. This first catalytic Pauson-Khand reaction (PKR) with an unstrained alkene affords 1, a precursor of methyl-trans-dihydrojasmonate that is important for the perfumery industry, in about 50% yield. The main byproducts of this PKR were also identified and possible routes for their formation proposed.