Treatment of 1-allenyl-1-diethynyl acetates 1 in the presence of a Au or Pt catalyst (5 mol %) in toluene at room temperature, followed by methanolysis, gave 4-methylene-2-cyclopentenones 2. The new cationic bisoxazoline(box)-Au(III) complex, [(S,S)-phbox-AuCl2]SbF6 or [(R,R)-bnbox-AuCl2]SbF6 accelerated the reaction, providing 2 in moderate yield (60-69%).
