A concise and highly convergent three-step total synthesis of the lactarane natural product, pyrovellerolactone, is described. The key step involves a regio-and diastereoselective rhodium-catalyzed [(3+ 2)+ 2] carbocyclization of an alkenylidenecyclopropane with a 4- hydroxybut-2-ynoate followed by an in situ intramolecular lactonization to generate the tricyclic core in a single operation. This represents the first example of a higher-order [3+ 2 ...
