Asymmetric synthesis of ent-fragransin C1

Abstract

The first asymmetric synthesis of ent-fragransin C₁ was reported. The key step involves an intramolecular C–O bond formation (furan ring formation) via chemoselective generation of the benzylic carbocation leading to the 2,3-anti-3,4-syn-4,5-anti-tetrahydrofuran moiety as a single diastereomer in good yield. Our synthesis confirms that ent-fragransin C₁ possesses 2R,3R,4S,5S configurations.