Aromatic acid derivatives from the lateral roots of Aconitum carmichaelii

Seven new aromatic acid derivatives (1–7), together with five known analogs, were isolated from the lateral roots of Aconitum carmichaelii. Structures of the new compounds were determined by spectroscopic and chemical methods as 4-methyl ( ? )-(R)-hydroxyeucomate (1), 4-butyl ( ? )-(R)-hydroxyeucomate (2), 4-butyl-1-methyl (+)-(R)-2-O-(4′-hydroxy-3′-methoxybenzoyl)malate (3), 1-butyl-4-methyl (+)-(R)-2-O-(4′-hydroxy-3′-methoxybenzoyl)malate (4), dimethyl (+)-(R)-2-O-(4′-hydroxy-3′-methoxybenzoyl)malate (5), dimethyl (+)-(R)-2-O-(4′-hydroxybenzoyl)malate (6), and methyl ( ± )-3-(4′-hydroxy-3′-methoxyphenyl)-3-sulfopropionate (7), respectively. Compounds 1 and 2 are 2-benzylmalates (eucomate derivatives), 3–6 belong to 2-O-benzoylmalates, and 7 is a rare phenylpropionate containing a sulfonic acid group. The absolute configurations of eucomate derivatives were confirmed by X-ray crystallographic analysis of 4-methyl eucomate (11).