“…The organic layer was dried over MgSO 4 , filtered and concentrated under reduced pressure. The crude azide was subjected to flash silica gel chromatography to give 0.47 g (93%) of azide 53 as a yellow oil; IR (thin film) 2951, 2108, 1739, and 1315 cm −1;1 H-NMR (CDCl 3 , 400 MHz) δ 1.96 (p, 2H, J = 7.2 Hz), 2.82 (t, 2H, J = 7.2 Hz), 3.33 (t, 2H, J = 6.8 Hz), 3.87 (s, 3H), and 7.12 (s, 1H); 13 -5-[3-(3a-methyl-2-oxo-2,3,3a,4,5,6-hexahydroindol-1-yl)propyl]-furan-2-carboxylic Acid Methyl Ester (56)…”