ural products often contain the (Z)-alkene functionality. As the E isomer is thermodynamically more stable, any synthesis of a (2)-alkene requires that conditions be sufficiently mild to retain the 2 configuration. In the case of the conjugated S (Z)-alkenals the propensity to isomerize is exceptionally high. 6 Although many catalytic semihydrogenation methods exist for selectively reducing alkynes to (2)-alkenes,'an alternative route has been developed in ...