Abietane Diterpenes from Clerodendron cyrtophyllum.

Abstract

Tow novel abietane derivatives, cyrtophyllones A (1) and B (2), together with six known compounds, teuvincenone F (3), unicinatone (4), sugiol (5), friedelin (6), clerodolone (7), stigmasta-5, 22, 25-trien-3β-ol (8) and clerosterol (9), were isolated from the stem of Clerodendron cyrtophyllum. One of the abietane diterpenes, cyrtophyllone A, possesses a rearranged-abietane skeleton wich contains a 17(15-16)-abeo-abietane framework. The stereo-structure proposed for 1 was characterized as 16(S)-12, 16-epoxy-11, 14-dihydroxy-6-methoxy-17(15-16)-abeo-abieta-5, 8, 11, 13-tetraen-7-one on the basis of spectral analysis (UV, IR, MS, two dimensional (2D) NMR and CD) and X-ray diffraction. The structure of 2 was also characterized as (+)-11, 12, 16-trihydroxy-abieta-8, 11, 13-trien-7-one by a combination of spectroscopic comparison with sugiol.