Reaction Steps
Methanesulfonyl chloride (0.57 mL, 7.4 mmol) was added dropwise to a solution of 1-(t-butyloxycarbonyl)-3-(hydroxymethyl)-6-nitroindoline (1.21 g, 4.11 mmol) and Et3N (1.15 mL, 8.2 mmol) in CH2Cl2 (70 mL) at 0° C., and the pale yellow solution stirred for 5 min. Water was added, the mixture was extracted with CH2Cl2 (×2), and the extracts dried (Na2SO4) and evaporated. The crude mesylate was dissolved in DMF (10 mL) with LiCl (0.70 g, 16 mmol) and the mixture stirred at 80° C. under nitrogen for 1 h. The DMF was evaporated, the residue dissolved in EtOAc and water, extracted once more with EtOAc, and the organic extracts dried (Na2SO4) and evaporated. Dry column chromatography, eluting with EtOAc/petroleum ether (1:9), gave title compound as pale yellow foam (1.12 g, 87%). A sample was crystallised from benzene-petroleum ether to give a yellow crystalline solid, mp 111-111.5° C. 1H NMR (CDCl3) δ8.67, 8.34 (2 x br s, 1H, H-7), 7.86 (dd, J=8.2, 2.2 Hz, 1H, H-5), 7.35 (d, J=8.2 Hz, 1H, H-4), 4.22 (dd, J=11.6, 9.6 Hz, 1H, H-2), 4.04-3.97 (m, 1H, H-2), 3.82-3.74 (m, 2H, CHHCl, H-3), 3.68-3.62 (m, 1H, CHHCl), 1.60 (s, 9H, t-Bu); 13C NMR δ151.8, 149.0, 144 (br), 138 (br) (C-6,8,9, NCO2), 124.6, 117.8, 110.0 (C-4,5,7), 82.0 (OCMe3), 52.4 (C-2), 46.3 (CH2Cl), 41.7 (C-3), 28.4 (C(CH3)3). Anal. Calculated for C14H18ClN2O4 : C, 53.8; H, 5.5; N, 11.3; Cl, 11.3. Found: C, 54.0; H, 5.5; N, 9.1; Cl, 11.5%.
