Isolation and Synthesis of an α-Malamic Acid Derivative from Justicia ghiesbreghtiana

A polar extract of leaves of Justicia ghiesbreghtiana yielded N-(2-hydroxy-4,5-dimethoxyphenyl)-(S)-α-malamic acid, 1. Incomplete spectral analysis yielded a hypothetical structure, which was then proven by total synthesis. Coupling of the trifluoroacetate of malic anhydride (trifluoroacetoxysuccinic anhydride) with an arylamine provided the key to regiospecific preparation of the α- rather than β-malamic acids.