Improved Second Generation Iron Pincer Complexes for Effective Ester Hydrogenation

Hydrogenation of esters to alcohols with a well-defined iron (PNP)-P-iPr2 pincer complex has been recently reported by us and other groups. We now introduce a novel and sterically less hindered (PNP)-P-Et2 congener that provides superior catalytic activity in the hydrogenation of various carboxylic acid esters and lactones compared to the known complex. Successful hydrogenation proceeds under relatively mild conditions (60 degrees C) with lower catalyst loadings.