Total synthesis of four callyspongiolide stereoisomers led to unambiguous assignment of relative and absolute stereochemistry of the natural product. Key features of the convergent, fully stereocontrolled route include the use of Krische allylation, Kiyooka Aldol reaction, Kociénski-Julia olefination, Still-Gennari olefination, Yamaguchi macrocyclization, and Sonogashira coupling reaction. Biological evaluation of the synthesized compounds against an array of cancer cells revealed that the stereochemistry of the macrolactone core played an important role.

The method described here allows rapid and convenient identification of the coumarins in A. dahurica, and may be applied to other herbal medicines containing linear furanocoumarins.

The first solution-phase total synthesis of teixobactin was completed with a 5.6% yield over 20 steps.