Abstract
Betulin, a lupane-type pentacyclic triterpene abundant in birch bark, is a useful natural scaffold for semisynthetic medicinal chemistry and process-oriented natural product chemistry. This review examines betulin 3,28-diacetate as an important derivative that is readily prepared, easily purified as a crystalline compound, and useful both as a target molecule and as a protected intermediate for further functionalization. The article surveys three connected areas: access to betulin from birch biomass, acetylation methods at labor-atory and process scale, and the synthetic utility of the diacetate in preparing more ad-vanced lupane derivatives. It summarizes extraction, purification, and analytical charac-terization of betulin, including melting-point analysis, chromatography, IR spectroscopy, NMR spectroscopy, and mass spectrometry. The review also compares classical acetyla-tion using acetic anhydride and acid catalysts with base-mediated approaches and green-er or more process-relevant variants, including direct bark acetylation and supercritical carbon dioxide-assisted isolation. Overall, betulin 3,28-diacetate is a practical and versa-tile intermediate for access to monoacetates, oxidized derivatives, and other lupane com-pounds, while further progress depends on improved catalyst choice, solvent replacement, process intensification, and analytical standardization.