In previous reports, we have described the synthesis and hepatoprotective activity of a variety of esters – 2-arylidene derivatives of betuline, lupol, and methylbetulonate [1, 2]. The present report presents data on the synthesis and study of the anti-inflammatory and antiulcer activities of 2-methylideneureido derivatives of betulonic acid, methylbetulonate, and lupenone. 2-Hydroxymethylene derivatives (IIa – IIc) were prepared by reaction of betulonic acid (Ia), methylbetulonate (Ib), and lupenone (Ic) with ethyl formiate in the presence of sodium methylate, with yields of 89 – 95%. Interaction of these compounds with urea and thiourea leads to the formation of 2-methylideneureido (IIIa – IIIc) and thioureido (IIId – IIIf) derivatives. The structures of these compounds were confirmed by IR, UV, and NMR spectra (see Tables 1, 2) and by comparison with published data for lupane triterpenoids [3 – 5]. The IR spectra of compounds IIa – IIc included, along with absorption peaks typical of these triterpenoids, bands in the region 3160 – 3150 cm –1 , due to the appearance of OH groups on the hydroxymethylene fragment [6]. In the 13 C NMR spectrum, the C-3 signal showed strongfield shifts compared with the signals in the initial 3-ketotriterpenoids, and also contained new signals corresponding to the C-1 atoms at 188.8 – 188.9 ppm, while the 1 H NMR spectra acquired weakfield signals at 8.52 – 8.60 ppm and 14.65 – 14.85 ppm corresponding to protons in =CH–OH and =CH–OH hydroxymethyl substituents. Analogous signals were also seen in the spectra of the formyl derivative of oleanolic acid [7]. The 13 C NMR spectra of compounds IIIa – IIIf showed resonating C-1 carbon atoms at 139.9 – 140.0 and 141.5 – 141.7 ppm, along with signals from the carbon atoms in the ureide fragments C=O and C=S at 155.3 – 155.5 and 182.4 – 182.6 ppm respectively. In addition, the 1 H NMR spectra of 2-methylideneureido (IIIa – IIIc) and thioureido (IIId – IIIf) derivatives showed interaction of the protons of these fragments in the form of doublets at 7.17 – 7.25 and 7.65 – 7.70 ppm, and 11.35 – 11.45 and 11.68 – 11.75 ppm.