Usnic Acid. XVI. Alkaline Degradation of Dihydrousnic Acid

金沢大学大学院自然科学研究科分子作用学金沢大学薬学部The structure of a new alkaline degration product of 1-dihydrousnic acid was elucidated as 5-acety-1,2,3,3a,7,7a-hexahydro-2,6-dihydroxy-1,2,3a-trimethyl-4-oxo-4H-inden-3,3-dicarboxylic acid (I) by chemical and spectral studies, together with X-ray analysis. The mechanism of formation of I from 1-dihydrousnic acid is discussed