Total Synthesis of (+)-Iresin

The first asymmetric total synthesis of (+)-iresin (4), an historically important ent-Drimane sesquiterpene lactone, was realized from aldehyde 3 via cyclic orthoester 6 in 5 steps. Notable transformations in this synthesis include a tandem trifluoroperacetic acid (TEPAA)-mediated Baeyer-Villiger oxidation-olefin epoxidation-epoxy ester cyclization, regioselective Burgess dehydration, and regioselective Fetizon oxidative lactonization.