(Chemical Equation Presented) Three-component coupling reactions of an alkyne, an enone, and a diboron reagent provide access to highly substituted alkenyl boronates in good to excellent yields (see scheme). The coupling is highly regio- and stereoselective, and the products are amenable to further functional-group transformations. R1,R2=H, alkyl, aryl, CO2Me; R3=alkyl, Ph; R4,R5=H, alkyl. © 2009 Wiley-VCH Verlag GmbH & Co. KGaA.