C-13 AND H-1-NMR ASSIGNMENTS FOR A SERIES OF DEHYDROABIETIC ACID-DERIVATIVES

Reliable assignments were made for a series of nitro and amine C ring- substituted dehydroabietic acid derivatives, the main resin acid prese nt in disproportionated rosin and an important intermediate in the che mical industry. A combination of 1D and 2D NMR techniques, including H ETCORR, COSY and DEFT experiments, was used. Quaternary carbon atoms, mainly aromatic substituted, require care owing to assignment difficul ties that are based on calculated data and are confirmed by long-range H-1, C-13 NMR correlation with selective INEPT and the proton-detecte d HMBC experiment.