One-pot synthesis of alpha,beta-unsaturated ketones through sequential alkyne dimerization/hydration reactions using the Hoveyda-Grubbs catalyst

Herein we report a sequential one-pot alkyne dimerization/hydration protocol for the regioselective synthesis of alpha,beta-unsaturated ketones in quantitative yields. The alkyne dimerization reactions of terminal arylacetylenes proceeded with high regioselectivity in the presence of the Hoveyda-Grubbs 2nd generation catalyst (1 mol%) and tricyclohexylphosphine (4 mol%). The hydration reactions of in situ formed 1-aryl-3-en-1-ynes proceeded very rapidly in the presence of CCl3COOH/p-TsOH center dot H2O, yielding the corresponding unsaturated ketones within 15 minutes in quantitative yields. Different arylacetylene derivatives were converted to the corresponding alpha,beta-unsaturated ketones in quantitative yields (94-95%) using sequential one-pot alkyne dimerization/hydration reactions.