Ruthenium catalyzed hydrogenation of methyl phenylacetate under low hydrogen pressure

PhCH2CO2Me has been efficiently hydrogenated to yield PhCH2CH2OH (1) and PhCH2CO2CH2CH2Ph (2) even under relatively low hydrogen pressure (<10 atm) by using ruthenium-phosphine catalysis composed of Ru(acac)(3), P(n-C8H17)(3) in the presence of Zn. Effect of both P(n-C8H17)(3) and Zn plays an essential role in order for this hydrogenation to proceed catalytically. Although the activity was not strongly influenced by the hydrogen pressure employed, the observed activity was strongly dependent upon the reaction temperature, substrate concentration, and solvent used. We assume that ruthenium hydride species plays an important role in this catalysis cycle. (C) 2002 Elsevier Science B.V. All rights reserved.