34 使君子の成分キスカル酸の構造 34 AN ASCARICIDAL PRINCIPLE OF QUISQUALIS FRUCTUS : THE CHEMICAL STRUCTURE OF QUISQUALIC ACID
A colorless needle crystalline, mp 187-188°(decomp.), C_5H_7O_5N_3 was isolated from Quisqualis Fructus (seeds of Quisqualis indica, and Q. indica var. villosa, Combretaceae), a popular ascaricidal crude drug in China and Japan. The compound was considered to be an unknown acidic amino acid and an active principle. So it was named quisqualic acid after the genus name Quisqualis. The chemical structure of quisqualic acid was consedered to be N^2-L-alanyl-3,5-dioxo-1,2,4-oxadiazolidine(Ia) or N^4-L-alanyl-3,5-dioxo-1,2,4-oxadiazolidine (Ib) on the basis of chemical and spectral data. Therefore Ia and Ib were synthesized by routes shown in the chart 2 and 3, respectively. Ib did not agree with quisqualic acid but Ia was identified with the authentic sample. Thus, the structure of quisqualic acid was confirmed to be N^2-L-alanyl-3,5-dioxo-1,2,4-oxadiazolidine satisfactorily. Quisqualic acid is the first instance of natural compound containing 1,2,4-oxadiazolidine ring.
天然有機化合物討論会講演要旨集 16(0), 256-263, 1972