Reaction Steps
Glycosidated indole 34 (3.7 g, 4.2 mmol) in 60 mL THF/MeOH (1:1) was treated with 10% Pd/C (1.5 g) and hydrogenated in a Parr apparatus at 40 psi for 23 h. The reaction mixture was filtered through a bed of Celite and the filter cake was washed with THF (20 mL) and EtOH (20 mL). To avoid any air oxidation, L-ascorbic acid (0.37 g) was added to the filtered solution. The solution was concentrated and chromatographed on silica gel using CHCl3/i-PrOH (7:1) to render the product 35 (1.6 g, 48%) as a brown foam: Rf=0.20 (7:1 CHCl3:iPrOH); 1H NMR (DMSO) 6.5-7.5 (m, 11H), 5.7 (d, 1H, J=7.9 Hz), 5.5 (t, 1H, J=9.6 Hz), 4.9-5.2 (m, 4H), 4.7 (d, 1H, J=9.9 Hz), 3.6 (s, 3H), 3.3 (s, 8H), 2.1 (s, 3H), 1.9-2.2 (m, 9H), 1.5-1.9 (m, 8H); 13C NMR (CDCl3) 170.0, 169.0, 167.0, 157.0, 156.5, 150.0, 138.0, 131.7, 131.6, 130.0, 127.3, 116.9, 114.7, 112.0, 111.0, 108.0, 104.5, 98.8, 72.6, 71.8, 71.1, 69.1, 64.4, 55.0, 55.2, 53.0, 47.0, 26.7, 23.6, 20.6, 20.5, 9.5; IR (KBr): νmax 3427, 3037, 2935, 2612, 1757, 1612, 1510, 1462, 1374, 1227, 1040 cm−1; LC/MS (ESI) retention time=13.0, M+H+=787.
