Reaction Steps
A solution of benzoyl chloride (1.61 g, 11.47 mmol) in CH2Cl2 (15 ml) was added dropwise to a stirred ice cold mixture of (1S,9S) t-butyl 9-amino-6,10-dioxo-1,2,3,4,7,8,9,10-octahydro-6H-pyridazino[1,2-a][1,2]diazepine-1-carboxylate (GB 2,128,984; 3.1 g, 10.43 mmol), dry CH2Cl2 (20 ml) and diisopropylethylamine (4.54 ml, 26.06 mmol). The mixture was kept cold for 1 h then left at room temperature for 0.5 h. The mixture was diluted with CH2Cl2, washed twice with brine, dried (MgSO4) and concentrated. The residue was purified by flash chromatography (0-5% methanol in CH2Cl2) to afford 211e (4.0 g, 96%) of a colourless glass: mp 74-76° C.; [α]D30 −75.0° (c 0.12, CH2Cl2). IR (KBr) 3350, 2979, 2938, 1736, 1677, 1662, 1536, 1422, 1276, 1250, 1155; 1H NMR (CDCl3) δ 8.72 (2H, m), 7.53-7.40 (3H, m), 7.07 (1H, d, J=7.2), 5.30 (1H, dd, J=3.0, 5.8), 5.12 (1H, m), 4.66 (1H, m), 3.51 (1H, m), 2.90 (2H, m), 2.38 (1H, dd, J 13.2, 6.8), 2.25 (1H, m), 1.9 (2H, m), 1.70 (1H, m). Anal. Calcd for C21H27N3O5 0.5H2O: C, 61.45; H, 6.88; N, 10.24. Found C, 61.69; H, 6.71; N, 10.18.
