Dehydrogenative Coupling of Ethanol and Ester Hydrogenation Catalyzed by Pincer-Type YNP Complexes

The “Y” donor group (Y = −OMe, −SEt, −PPh 2, −NH 2, −NMe 2, −Py, pyrrolidinyl, quinolyl) of the pincer-type ruthenium complexes RuHCl(CO)[κ 3 -YNP] has a dramatic influence on the catalytic activity in the dehydrogenative homocoupling and cross-coupling of ethanol and ester hydrogenation reactions. The observations are connected with the mechanisms of the catalytic reactions, and this paper provides evidence for ester C–O bond formation/cleavage assisted by the bifunctional catalysts in an outer-sphere fashion, reminiscent of the Tishchenko chemistry.