Ruthenium(II) pi greco-alkyne and vinylidene complexes derived from glycoynitols: new precursors for water soluble unsaturated carbenes

A new class of precursors for water-soluble unsaturated carbenes was synthesized by reaction of [Cp*RuCl(PMe3)2] with a terminal alkyne and a propargyl alcohol, each bearing a polyhydroxylated lateral chain derived from d-xylose. In the reaction with the terminal glycoynitol, the presence of a pair of noninterconverting ?-alkyne intermediates of [Cp*Ru(PMe3)2]+ species was observed for the first time and the kinetics of isomerization to the same vinylidene species measured by NMR experiments.