Structure of Lasiocarpic Acid

Abstract

IN view of recent publications^1,2 dealing with the structures of the esterifying acids of the pyrrolizidine group of alkaloids, it seems desirable to place on record the following data relating to lasiocarpic acid obtained from the alkaloid lasiocarpine. Lasiocarpine, together with heliotrine, was first isolated by Men'shikov³ from Heliotropium lasiocarpum F. and M. Later, Trautner and Neufeld⁴ obtained lasiocarpine from H. europæum L. growing in Australia and found it to be accompanied by isoheliotrine, a base differing from Men'shikov's heliotrine only in respect of its optical rotation. Trautner and Neufeld's work has been repeated and confirmed except for the yields of the two alkaloids. Lasiocarpine from H. europæum is clearly identical with the alkaloid from H. lasiocarpum, giving, on hydrolysis and hydrogenolysis, products the properties of which are in complete agreement with those described by Men'shikov and Schdanovitch³. Likewise, isoheliotrine gives, on hydrolysis and hydrogenolysis, products having the same properties, including optical rotation, as those reported from heliotrine, despite the differences in rotation of the parent bases.