Carbon‐13 NMR spectra of some labdane diterpenoids

Abstract

Abstract Carbon‐13 signal assignments of the labdane diterpenoids phlogantholide‐A, its diacetate and isophlogantholide‐A are reported. The assignments of the 13 C NMR signals of 14‐deoxyandrographolide and its diacetate, made earlier, have now been confirmed by lanthanide shift studies on the former and also by 13 C spectral studies on anhydroandrographolide diacetate and 14‐deoxy‐11,12‐didehydroandrographolide diacetate.