3.1. Chemistry

Dehydroabietic acid (DHA) was obtained from commercial rosin as described in [41]. Oleanolic acid (OA) was isolated from the aerial parts of Fabiana imbricata [42]. The triazole derivatives were prepared as described previously (Figure 1) [41,42]. Briefly, DHA was methylated with CH₂N₂ to afford dehydroabietic acid methyl ester. Reduction of the methyl ester with LiAlH₄ in THF gave the corresponding alcohol (dehydroabietinol). Starting from DHA and its alcohol, 16 abietane-triazole compounds were obtained using click chemistry [41]. The alkyl esters of DHA and its alcohol were prepared using N,N-dicyclohexylcarbodiimide (DCC)/ dimethylaminopyridine (DMAP) and appropriate alcohol or acid with alkyl function. The alkynyl esters were treated with different azides in t-BuOH/H₂O using CuSO₄.5H₂O and sodium ascorbate to obtain the derivatives 1–16 (Figure 1).

Oleanolic acid (OA) derivatives contained 1,2,3-triazoles linked to the 3-O function and a free or methylated COOH function at C-28 were prepared as reported [42]. OA was treated with the appropriate alkyne acid/DCC/DMAP to afford the alkynyl esters 17–20. The alkynyl esters and different azides were dissolved in CH₂Cl₂/H₂O (1:1), followed by click chemistry conditions (CuSO₄·5H₂O/sodium ascorbate) to afford compounds 21–34 (Figure 1).