Biphenyl Inhibits Stereomutation in Semihydrogenation of 4-Arylbut-2-yn-1-ols

Abstract

Semihydrogenation of 4-arylbut-2-yn-1-ols in the presence of a quinoline -deactivated palladium catalyst yielded mixtures of (Z)- and (E)-4-arylbut-2-en-1-ols. We find that stereomutation of the initially formed (Z)- alkene product is prevented if biphenyl (10% of the weight of the alkyne substrate) is included in the reaction mixture.