Reaction Steps
A solution of (R)-3-(N-benzyloxycarbonyl-pyrrolidin-2-ylcarbonyl)-5-bromo-1H-indole (1.04 g) in dry tetrahydrofuran (20 mL) was added dropwise to a stirred suspension of lithium aluminium hydride (0.27 g) in dry tetrahydrofuran (15 mL) at room temperature under an atmosphere of dry nitrogen. The mixture was heated under reflux with stirring for 18 hours and then cooled. Additional lithium aluminium hydride (50 mg) was added and refluxing was continued for an additional 3 hours. The mixture was again cooled, lithium aluminium hydride (40 mg) was added, and refluxing was continued for a further 18 hours. The mixture was cooled and water (0.44 mL) was carefully added with stirring, followed by 20% aqueous sodium hydroxide (0.44 mL), followed by more water (1.33 mL). The mixture was diluted with ethyl acetate and filtered through Celite (trademark) filter aid. The filtrate was washed with water, brine and then dried (Na2SO4). Evaporation of the solvent gave an oil which was chromatographed on silica gel. Elution with dichloromethane/ethanol/concentrated aqueous ammonia (90:10:0.5) gave the title compound as a solid (0.51 g), m.p. 137°-140° C. (from dichloromethane/hexane); IR (KBr) 1620, 1595, 1570, 1480, 1450, 1435 cm-1 ; 1H NMR (DMSO-d6) δ11.05 (br s, 1H), 7.65 (br d, 1H), 7.31 (d, J=8.6 Hz, 1H), 7.21 (br d, 1H), 7.16 (dd, J=1.8 and 8.6 Hz, 1H), 3.03-2.94 (m, 2H), 2.47 (dd, J=9.2 and 14.0 Hz, 1H), 2.36-2.26 (m, 1H), 2.33 (s, 3H), 2.09 (dd, J=8.7 and 17.3 Hz, 1H), 1.73-1.38 (m,4H); 13C NMR (DMSO-d6) δ134.8, 129.5, 124.7, 123.2, 120.7, 113.4, 112.1, 110.9, 66.1, 57.0, 40.5, 30.9, 29.1, 21.6; LRMS, m/z (relative intensity) 294 (M+ with 81Br, 1) 293 (2) 292 (M+ with 79Br, 1), 210 (14), 208 (15), 154 (8), 129 (42), 128 (19), 101 (26) 85 (57) 84 (100), 83 (30); [α]25D =+62° (methanol, c=0.10). Anal Calcd for C14H17N2Br. 0.25 H2O: C, 56.48; H, 5.93; N, 9.41. Found: C, 56.65; H, 5.69; N, 9.23.
