The Decomposition of Lasiocarpic and Echimidinic Acids in Hydrochloric Acid

Abstract

In concentrated hydrochloric acid at 100 °C, lasiocarpic acid is readily decomposed with formation principally of acetaldehyde, dimethylpyruvic acid, and α-keto-ββ-dimethyl-γ-valerolactone. Echimidinic acid is similarly and more rapidly decomposed while trachelanthic and heliotric acids are stable at 100 °C. In dilute hydrochloric acid, lasiocarpic acid is slowly converted into acetaldehyde, acetone, dimethylpyruvic acid, (+)-2-methoxy-4-methylpentan-3-one (IX), 2-methylpent-1-en-3-one (XI), and an unidentified compound. The isolation of IX shows that lasiocarpic and heliotric acids have the same absolute, configuration at the asymmetric carbon atom which bears the methoxyl group.