Reaction Steps
Following the procedure 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 2-(2-oxooxazolidin-3-yl)ethyl 4-methylbenzenesulfonate to replace 2-(bromomethyl)-5-(trifluoromethyl)furan, 1′-[2-(2-oxo-1,3-oxazolidin-3-yl)ethyl]-5,6-dihydrospiro[benzo[1,2-b:5,4-b′]difuran-3,3′-indol]-2′(1′H)-one was obtained (46%) as a colorless solid: mp 185-186° C.; 1H NMR (300 MHz, CDCl3) δ7.33 (dd, J=7.8, 7.8 Hz, 1H), 7.18 (d, J=7.3 Hz, 1H), 7.08 (dd, J=7.3, 7.3 Hz, 1H), 6.99 (d, J=7.8 Hz, 1H), 6.50 (s, 1H), 6.40 (s, 1H), 4.78 (ABq, 2H), 4.53 (t, J=8.6 Hz, 2H), 4.33-4.22 (m, 1H), 4.21-4.00 (m, 2H), 3.93-3.58 (m, 4H), 3.57-3.43 (m, 1H), 3.05-2.91 (m, 2H); 13C NMR (75 MHz, CDCl3) δ 178.8, 161.8, 161.3, 158.7, 141.7, 132.4, 129.0, 124.1, 123.7, 120.0, 119.0, 108.3, 93.2, 80.5, 72.5, 62.1, 57.7, 44.3, 41.7, 37.3, 29.0; MS (ES+) m/z 393.3 (M+1).
