3-Chloro-2-formyl-17β-formyloxy-5α-androstane 2c (120 mg, 0.34 mmol) was added to a suspension of acetamidine hydrochloride (160 mg, 1.69 mmol) and potassium carbonate (280 mg, 2.0 mmol) in DMF (5 mL). The mixture was stirred at 60–65°C for 6 h until the complete conversion of the intermediates (TLC monitoring). The resulting mixture was cooled to room temperature and the solvent was removed under reduced pressure. The product was purified by column chromatography using chloroform/MeOH, 6:1, to obtain colorless solid (41 mg, 29% yield). Rf 0.30 (CHCl3:MeOH, 5:0.3; visualized by UV light at 254 nm); m.p. 210–212°C. 1H NMR (600 MHz, DMSO-d6), δ: 0.62 (s, 3H, 18-CH3), 0.68 (s, 3H, 19-CH3), 0.65–0.71 (m, 1H, 9-CH), 0.78–0.88 (m, 2H, 7-CH2, 14-CH), 0.90–0.96 (m, 1H, 12-CH2), 1.11–1.18 (m, 2H, 6-CH2, 15-CH2), 1.22–1.39 (m, 5H, 8-CH, 11-CH2, 16-CH2), 1.40–1.50 (m, 3H, 5-CH, 6-CH2, 15-CH2), 1.60 (d, J = 12.0 Hz, 1H, 7-CH2), 1.64 (d, J = 16.8 Hz, 1H, 1-CH2), 1.71 (d, J = 12.6 Hz, 1H, 12-CH2), 1.80 (s, 3H, 4′-CH3), 1.82 (s, 3H, 6′-CH3), 2.00–2.05 (m, 1H, 4-CH2), 2.06 (d, J = 16.8 Hz, 1H, 1-CH2), 2.14–2.19 (m, 1H, 4-CH2), 3.39–3.43 (m, 1H, 17-CH), 4.40 (br.s, 1H), 5.48 (s, 1H, 2′-CH), 9.50 (br.s, 1H). 13C NMR (150 MHz, DMSO-d6), δ: 11.1 (18-CH3), 11.6 (19-CH3), 20.3 (4′-CH3, 6′-CH3), 20.4 (11-CH2), 23.0 (15-CH2), 27.2 (6-CH2), 29.8 (16-CH2), 30.6 (7-CH2), 34.1 (10-C), 35.0 (8-CH), 36.4 (12-CH2), 38.1 (4-CH2), 39.1 (1-CH2), 42.4 (13-C), 42.5 (5-CH), 50.4 (14-CH), 53.1 (9-CH), 70.7 (2′-CH), 80.0 (17-CH), 123.0 (3-C), 134.0 (2-C), 152.2 (4′-C, 6′-C). IR (KBr), cm−1: 3205 (NH), 2926, 2872 (CH), 1708, 1665 (C = C, C = N), 1498, 1469, 1444, 1380, 1380, 1338, 1250. HRMS (ESI) for C24H37ClN3O ([M+H]+): calcd 418.2620, found 418.2610.