Four new cassane diterpenoid amides from Erythrophleum suaveolens [(Guill. et Perr.), Brenan]

Four new cassane diterpenoid amides, 1–4 and six known cassane diterpenoid amides have been isolated from the stem bark of Erythrophleum suaveolens. The isolated compounds were subjected to phytochemical investigation. The structures of those compounds were elucidated on the basis of one- and two-dimensional NMR, HRMS and ESIMS analyses. Nor-cassamide was obtained as crystal and characterized by X-ray method. This was the first crystallographic description of cassane diterpenoid and it allowed to confirm the absolute configuration of the stereogenic centers and the stereochemistry of the double exocyclic bond.