3β-Acetoxy-17-chloro-16-formylandrosta-5,16-diene 2b (122 mg, 0.32 mmol) was added to a suspension of guanidine acetate (58 mg, 0.48 mmol) and potassium carbonate (134 mg, 0.97 mmol) in methanol (10 mL). The resulting mixture was refluxed for 6 h until the complete conversion of the intermediates (TLC monitoring). The resulting mixture was cooled to room temperature. The precipitate that formed was filtered, washed with H2O (5 mL), and dried. The workup afforded the analytically pure product as colorless solid (92 mg, 84% yield). Rf 0.56 (CHCl3:MeOH, 5:0.2; visualized by UV light at 254 nm). The spectral data are consistent with those reported by Matsumoto et al. (2003). m.p. 342–344°C [m.p.lit (Matsumoto et al., 2003) = 308–312°C]. 1H NMR (600 MHz, DMSO-d6at333K), δ: 0.90 (s, 3H, 18-CH3), 1.03 (s, 3H, 19-CH3), 0.98–1.10 (m, 2H, 1-CH2, 9-CH), 1.34–1.42 (m, 1H, 2-CH2), 1.42–1.50 (m, 1H, 12-CH2), 1.44–1.52 (m, 1H, 14-CH), 1.55–1.83 (m, 6H, 1-CH2, 2-CH2, 7-CH2, 8-CH, 11-CH2), 1.99–2.09 (m, 2H, 7-CH2, 12-CH2), 2.09–2.22 (m, 2H, 4-CH2), 2.29 (dd, J = 6.0, 13.8 Hz, 1H, 15-CH2), 2.55 (dd, J = 6.0, 13.8 Hz, 1H, 15-CH2), 3.24–3.32 (m, 1H, 3-CH), 4.41 (br.s, 1H, OH), 5.30–5.32 (m, 1H, 6-CH), 6.11 (br.s, 2H, NH2), 7.98 (s, 1H, H-4′). 13C NMR (125 MHz, DMSO-d6at333K), δ: 16.4 (18-CH3), 18.8 (19-CH3), 19.9 (11-CH2), 26.6 (15-CH2), 30.1 (7-CH2), 30.5 (8-CH), 31.2 (2-CH2), 32.5 (12-CH2), 36.1 (10-C), 36.6 (1-CH2), 42.0 (4-CH2), 45.0 (13-C), 50.0 (9-CH), 55.1 (14-CH), 69.7 (3-CH), 119.6 (6-CH), 121.0 (16-C), 141.5 (5-C), 152.2 (4′-CH), 162.6 (2′-C), 181.5 (17-C). IR (KBr), cm−1: 3535 (OH), 3368, 3314, 3159 (NH2), 2935, 2893, 2844 (CH), 1647 (NH2), 1608, 1559 (C = C, C = N). HRMS (ESI) for C21H30N3O ([M+H]+): calcd 340.2383, found 340.2382. Anal. calcd for C21H29N3O:C, 74.30; H, 8.6; N, 12.38. Found: C, 73.83; H, 8.65; N, 12.15.