Total Synthesis of Ostopanic Acid, a Plant Cytotoxin, via Cyclopropanation of 2-n-Hexylfuran

Article abstract of DOI:10.1021/jo00282a031

The cyclopropanation of 2-n-hexylfuran with ethyl 8-diazo-7-oxooctanoate catalyzed by dirhodium tetraacetate as a key step for synthesis of ostopanic acid is reported.This reaction allowed the preparation of ethyl ostopanate (5) and its unstable regioisomer (10) in 58percent yield.Exposure of the mixture to a catalytic amount of iodine in dichloromethane afforded pure ethyl ostopanate, which was converted to the target compound in two steps.