Abstract The gold-catalyzed transformation of allenyl acetals into 5-alkylidenecyclopent-2-en- 1-ones is described. The outcome of our deuterium labeling experiments supports a 1, 4- hydride shift of the resulting allyl cationic intermediates because a complete deuterium transfer is observed. We tested the reaction on various acetal substrates bearing a propargyl acetate, giving 4-methoxy-5-alkylidenecyclopent-2-en-1-ones 4 via a degradation of the ...
