Crystal and molecular structure of 3,5-dimethyl-1<Emphasis Type="Italic">H</Emphasis>-pyrazolide of 3-O-acetyl ursolic acid

3,5-Dimethyl-1H-pyrazolide of 3-O-acetyl ursolic acid (II) is obtained in the course of the interaction of 3 O-acetyl ursolic acid acyl chloride (I) and 3,5-dimethyl-1H-pyrazole. The crystal structure of compound II is determined from the single crystal XRD data (150 K, Bruker X8 Apex CCD autodiffractometer, MoK _α radiation). The crystals are rhombic, the unit cell parameters are as follows: a = 10.6034(2) Å, b = 12.4096(2)Å, c = 24.5972(5)Å, P2₁2₁2₁ space group. The structure consists of discrete acentric molecules. When pyrazolide II is boiled in the alcohol alkali solution, secondary hydroxyl is deacetylated and 3,5-dimethyl-1H-pyrazolide of ursolic acid IV is formed. Compounds II and IV are studied by NMR spectroscopy.