Gold-Catalyzed 1,3-Addition of a Sp3-Hybridized C-H Bond to Alkenylcarbenoid Intermediate

We report stereoselective synthesis of bicyclo[3.2.1]oct-6-en-2-ones through Au(l)-catalyzed cycloisomerization of an allenene-acetal functionality. This cyclization is mechanistically significant because it involves an unprecedented 1,3-addition of a Sp(3)-hybridized C-H bond to vinylcarbenoid moiety.