First Synthesis of Betulin 20-Acylhydrazones

Five 20-( N ′-acylhydrazinylidene)betulin derivatives have been synthesized in 39–49% yield starting from betulin by condensation of 3β,28-dihydroxy-29-norlupan-20-one (messagenin) with capric, cyclohexane­carboxylic, benzoic, and 2- and 4-hydroxybenzoic acid hydrazides. An efficient procedure has been proposed for the synthesis of messagenin in almost quantitative yield by low-temperature (–70°C) ozonolysis of betulin in ethanol, followed by treatment of the resulting peroxides with 15 equiv of glacial acetic acid.