Efficient catalytic hydrogenation of alkyl levulinates to γ-valerolactone

Efficient hydrogenations of neat alkyl levulinates to γ-valerolactone were achieved with low catalyst loadings of either PNP Ru or Ir complexes, respectively, in the presence of a small amount of a base at low temperature and H₂ pressure. Quantitative conversions and TONs reaching 9300 were achieved. Furthermore, we demonstrate the feasibility of the system to perform several cycles. Finally, deuterium labelling and NMR studies provide insight into the reaction mechanism.