Clerodenoids A—F: C‐ring Aromatized and/or Rearranged Abietane Diterpenoids from Clerodendrum chinense var. simplex

Main observation and conclusion As part of our continuing efforts toward the discovery of the biologically active diterpenoids from medicinal plants, six new C‐ring aromatized abietane diterpenoids, clerodenoids A—F (1—6), were isolated from Clerodendrum chinense . These C‐ring aromatized compounds mainly belonged to the rearranged abietane skeletons of 17(15→16)‐ abeo ‐abietane (2—4) and 17(15→16), 18(4→3)‐ diabeo ‐abietane (5 and 6). Their structures were elucidated by extensive spectroscopic data, X‐ray crystallography, and ECD calculation. Compounds 5 and 6 displayed strong antiproliferative activities against A549 and HL‐60 cell lines.