Phosphine-triggered complete chemo-switch: From efficient aldehyde-alkyne-amine coupling to efficient aldehyde-alkyne coupling in water

graph A phosphine ligand served as a remarkable chemo-switch for the silver-catalyzed reaction of alkynes with aldehydes in the presence of amines in water. Exclusive aldehyde-alkyne-amine coupling product was observed in the absence of phosphine, whereas in the presence of a phosphine ligand, exclusive aldehyde-alkyne coupling product was obtained.