Spectral assignments of new diterpenes from Hyptis martiusii Benth.

The structural characterization of two new abietanes and a new spiro-fused tricyclic diterpene isolated from the roots of Hyptis martiusii is described. The first member of a new class of rearranged abietane diterpenoids designated martiusane was characterized by the use of 1D NMR and several 2D shift correlated NMR pulse sequences (1H,1H-COSY, HMQC, HMBC and NOESY). Unambiguous 1H and 13C chemical shift assignments for all compounds are reported. Copyright 2004 John Wiley & Sons, Ltd.