Ent-3,4-seco-labdane and ent-labdane diterpenoids from Croton stipuliformis (Euphorbiaceae)

Three ent-3,4-seco-labdanes (1-3) and one ent-labdane (4) were isolated and identified from the leaves of Croton stipuliformis. The absolute stereochemistry for compound 4 was assigned by Mosher's method in the NMR tube.