Inexpensive Ruthenium NNS‐Complexes as Efficient Ester Hydrogenation Catalysts with High C=O vs. C=C Selectivities

Abstract Ru(NNS)(PPh 3 )Cl 2 (NNS=2‐(methylthio)‐N‐(pyridin‐2‐yl‐methyl)ethan‐1‐amine) was employed in the hydrogenation of α,β‐unsaturated esters, reaching selectivities for the allylic alcohol up to 95% in the hydrogenation of iso‐butylcinnamate. In addition, several ester substrates were hydrogenated with catalyst loadings as low as 0.05 mol%. Surprisingly, selectivity of the hydrogenation of the C=O vs the C=C bonds strongly depends on the solvent. magnified image