Complete 1H and 13C NMR assignments of clerodane diterpenoids of Salvia splendens

Unambiguous and complete assignments of H-1 and C-13 NMR chemical shifts for five clerodane diterpenes, four of them isolated from Salvia splendens (salviarin, splendidin and splenolides A and B) and one obtained by acetylation of splenolide A, are presented. The assignments are based on 2D shift-correlated [H-1,H-1-COSY, H-1,C-13-gHSQC-(1)J(C,H) and H-1,C-13-gHMBC-(n)J(C,H) (n = 2 and 3)] and nuclear Overhauser effect (NOE) experiments. The conformation of the rings of these compounds is supported by the 31(H,H) values and NOE results. Copyright (c) 2006 John Wiley & Sons, Ltd.