Sodium hydrogencarbonate (0.168 g) and tetrahydrofuran (20 ml) were added to a suspension of glycylglycine (0.15 g) in water (20 ml). After tetrahydrofuran (20 ml) and cholesteryl chloroformate (0.898 g) were added to the resulting transparent solution at 0° C., the mixture was stirred for an hour. The reaction mixture was concentrated under reduced pressure and, methanl (10 ml) and chloroform (10 ml) were added to the residue. By filtration, the transparent solution was obtained. The solvent was distilled off to give crude crystals (0.98 g). The crude crystals were then purified by silica gel chromatography to give N-(cholest-5-ene-3β-oxycarbonyl)glycylglycine (0.5 g) as white powders.
