An Empirical Study of Phosphine Ligands for the Methoxycarbonylation of Medium-Chain Alkenes

The methoxycarbonylation reaction provides a route to the synthesis of esters from medium-chain alkenes that may be used as fuel supplements. However, the known productive catalytic systems are expensive and/or unstable at elevated temperatures. Most of the data available on the methoxycarbonylation of alkenes is derived from ethylene and styrene as substrates. To broaden the scope, we conducted a comparative study of a range of phosphine ligands under comparable conditions for the methoxycarbonylation of 1-octene. The results demonstrate that a number of ligand structural motifs facilitate the process effectually. Furthermore, the critical importance of alkene isomerization and the acid/ligand and Pd/ligand ratios are presented.