All‐Carbon [3 + 3] Oxidative Annulations of 1,3‐Enynes by Rhodium(III)‐Catalyzed C—H Functionalization and 1,4‐Migration.

1,3-Enynes containing allylic hydrogens cis to the alkyne function as three-carbon components in rhodium(III)-catalyzed, all-carbon [3+3] oxidative annulations to produce spirodialins. The proposed mechanism of these reactions involves the alkenyl-to-allyl 1,4-rhodium(III) migration.