Expedient Synthesis of [5,5]- and [6,5]-Benzannulated Spiroketals from 1,1-Diacyl-2-vinyl Cyclopropanes

Palladium-mediated oxidative spirocyclization of 1,1-diacyl-2-vinylcyclopropanes afforded a small series of benzannulated 6,5- and 5,5-spiroketals. The rapid construction of these scaffolds proceeded in moderate to good yield (27-63%). However, efforts to thoroughly examine scope were hampered by both poor diastereoselectivity and, in the case of the 5,5-benzannulated spiroketal series, access to the requisite 1,3dicarbonyl starting materials.