Studies in the usnic acid series. III. The base catalyzed usnic acid–isousnic acid rearrangement. The synthesis of (+)-isousnic acid

Abstract

Investigations concerning the alkaline cleavage of (+)-isoxazolo[4,5-b]usnic acid (8) are described. During these studies a novel rearrangement from the 'normal' (usnic acid) to the 'iso' (isousnic) series was revealed. The rearrangement process was then utilized in the synthesis of (+)-isousnic acid (3).