Studies in the usnic acid series. IV. The base catalyzed usnic acid – isousnic acid rearrangement. Part II. An improved synthesis of (+)-isousnic acid

Abstract
Investigations concerning the alkaline cleavage of (+)-2H-[1,2]oxazocinousnic acid (3) are described. These studies provide an interesting rearrangement from the 'normal' (usnic acid) to the 'iso' (isousnic) series and, in turn, a high yielding sequence for the synthesis of (+)-isousnic acid (1).