Gold(I) Catalyzed Isomerization of 5-en-2-yn-1-yl Acetates:  An Efficient Access to Acetoxy Bicyclo[3.1.0]hexenes and 2-Cycloalken-1-ones

The gold(I) catalyzed rearrangement of 5-en-2-yn-1-yl acetates into functionalized acetoxy bicyclo[3.1.0]hexenes is described. The mild reaction conditions employed allow the efficient and rapid synthesis of a variety of such bicyclic compounds via a sequence of two gold(I)-catalyzed isomerization steps. Acetoxy bicyclo[3.1.0]hexenes products can be further transformed to 2-cycloalkenones by simple methanolysis.