Reaction Steps
Following the procedure as described in EXAMPLE 9 and making non-critical variations using 5,6-dihydrospiro[benzo[1,2-b:5,4-b′]difuran-3,3′-indol]-2′(1′H)-one to replace 3-methylspiro[furo[3,2-f][1,2]benzisoxazole-5,3′-indol]-2′(1H)-one, and methyl 3-(bromomethyl)benzoate to replace 2-(bromomethyl)-5-(trifluoromethyl)furan, methyl 3-[(2′-oxo-5,6-dihydrospiro[benzo[1,2-b:5,4-b′]difuran-3,3′-indol]-1′(2′H)-yl)methyl]benzoate was obtained (93%) as a colorless solid: mp 97-98° C. (hexanes/ethyl acetate); 1H NMR (300 MHz, CDCl3) δ8.04 (s, 1H), 8.02-7.96 (m, 1H), 7.58-7.52 (m, 1H), 7.49-7.42 (m, 1H), 7.25-7.17 (m, 2H), 7.09-7.00 (m, 1H), 6.78 (d, J=7.5 Hz, 1H), 6.56 (s, 1H), 6.45 (s, 1H), 5.16 (d, J=15.7 Hz, 1H), 5.02 (d, J=9.0 Hz, 1H), 4.89 (d, J=15.7 Hz, 1H), 4.74 (d, J=9.0 Hz, 1H), 4.60-4.52 (m, 2H), 3.93 (s, 3H), 3.13-2.96 (m, 2H); 13C NMR (75 MHz, CDCl3) δ178.1, 166.7, 162.0, 161.4, 141.9, 136.3, 132.8, 131.9, 130.9, 129.3, 129.2, 128.9, 128.4, 124.1, 123.7, 120.2, 120.1, 119.1, 109.2, 93.4, 80.7, 72.5, 57.9, 52.3, 43.9, 29.2; MS (ES+) m/z 428.1 (M+1).
