New Methyl Dehydroabietate Derivatives: Synthesis and Structural Characterization

Abstract

The synthesis of some new chalcone and pyrazole type derivatives of methyl dehydroabietate is described. All compounds were exhaustively characterized using NMR and MS techniques. In order to con®rm the information obtained by those techniques, the X-ray single crystal structures of methyl 12-acetyldehydroabietate and methyl 12-(4-methoxycinnamoyl)-dehydroabietate were determined. Molecular mechanics calculations were performed in order to evaluate the steric in¯uence of the bulk of the C-12 substituent on the conformational preference of the isopropyl group in these derivatives. The energy barriers of 52.3 and 53.6 kJ/mol found for the two compounds indicated that the C-12 substituent hinders the free rotation of the isopropyl group in both cases.

Synthesis of methyl 12-benzoyldehydroabietate in ionic liquid

“…In recent years, in order to prepare rosin-based functional compounds with high additional value, people have paid more attention to the modification of dehydroabietic acid. Many important rosin-based arone intermediates have been prepared through the Friedel-Crafts reaction on the aromatic ring of dehydroabietic acid [6,7]. Recently, Li et al [8] reported on the structure of methyl 12-benzoyldehydroabietate, which was synthesized under the conditions of methyl dehydroabietate and benzoyl chloride as raw materials, 1, 1, 2, 2-tetrachloroethane and AlCl 3 as solvent and catalyst, respectively, room temperature, and reaction time 24 h. The yield amounted to 81%.…”