3-Chloro-2-formyl-17β-formyloxy-5α-androstane 2c (108 mg, 0.30 mmol) was added to a suspension of guanidine acetate (53 mg, 0.45 mmol) and potassium carbonate (124 mg, 0.90 mmol) in methanol (10 mL). The mixture was refluxed for 4 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 water (5 mL), and dried. The workup afforded analytically pure product as colorless solid (91 mg, 89% yield). Rf 0.67 (CHCl3:MeOH, 5:0.2; visualized by UV light at 254 nm). The spectral data are consistent with those reported by De Ruggieri et al. (1962). m.p. > 350°C (m.p.lit > 300°C). 1H NMR (600 MHz, DMSO-d6), δ: 0.68 (s, 3H, 18-CH3), 0.69 (s, 3H, 19-CH3), 0.78–0.84 (m, 1H, 9-CH), 0.86–0.95 (m, 2H, 7-CH2, 14-CH), 0.98–1.06 (m, 1H, 12-CH2), 1.14–1.29 (m, 2H, 6-CH2, 15-CH2), 1.32–1.42 (m, 3H, 8-CH, 11-CH2, 16-CH2), 1.49–1.56 (m, 3H, 5-CH, 6-CH2, 15-CH2), 1.58–1.64 (m, 1H, 11-CH2), 1.64–1.70 (m, 1H, 7-CH2), 1.77–1.82 (m, 1H, 12-CH2), 1.83–1.89 (m, 1H, 16-CH2), 2.16 (d, J = 15.6 Hz, 1H, 1-CH2), 2.24 (dd, J = 12.6, 18.0 Hz, 1H, 4-CH2), 2.43–2.56 (m, 2H, 4-CH2, 1-CH2), 3.47 (t, J = 8.4 Hz, 1H, 17-CH), 4.18 (br.s, 1H, OH), 5.90 (br.s, 2H, NH2), 7.91 (s, 1H, H-4′). 13C NMR (125 MHz, DMSO-d6), δ: 10.8 (18-CH3), 10.9 (19-CH3), 20.2 (11-CH2), 22.7 (15-CH2), 27.8 (6-CH2), 29.6 (16-CH2), 30.5 (7-CH2), 34.5 (10-C), 35.0 (8-CH), 35.2 (4-CH2), 36.3 (12-CH2), 38.4 (1-CH2), 40.8 (5-CH), 42.1 (13-C), 50.4 (14-CH), 53.0 (9-CH), 79.8 (17-CH), 116.7 (2-C), 157.9 (4′-CH), 161.6 (2′-C), 164.2 (3-C). IR (KBr), cm−1: 3322, 3169 (NH2), 2969, 2923, 2905, 2849 (CH), 1659 (NH2), 1596, 1561 (C = C, C = N). HRMS (ESI) for C21H32N3O ([M+H]+): calcd 342.2540, found 342.2538.