Reaction Steps
Following the procedure as described in EXAMPLE 3 and making non-critical variations using 1-(diphenylmethyl)-5′,6′,7′,8′-tetrahydrospiro[indole-3,3′-naphtho[2,3-b]furan]-2(1′H)-one to replace 1′-(diphenylmethyl)-6-methoxy-5-methylspiro[1-benzofuran-3,3′-indol]-2′(1′H)-one, 5′,6′,7′,8′-tetrahydrospiro[indole-3,3′-naphtho[2,3-b]furan]-2(1′H)-one was obtained (80%) as a colorless solid: mp>230° C.; 1H NMR (300 MHz, CDCl3) δ 8.13 (s, 1H), 7.33-7.19 (m, 1H), 7.16 (d, J=7.4 Hz, 1H), 7.04 (dd, J=7.5, 7.5 Hz, 1H), 6.95 (d, J=7.7 Hz, 1H), 6.68 (s, 1H), 6.49 (s, 1H), 4.92 (d, J=9.0 Hz, 1H), 4.65 (d, J=9.0 Hz, 1H), 2.76-2.72 (m, 2H), 2.58-2.56 (m, 2H), 1.71 (t, J=3.2 Hz, 4H); 13C NMR (75 MHz, CDCl3) δ180.5, 158.7, 140.4, 139.0, 132.9, 130.2, 128.8, 126.0, 124.1, 123.6, 123.3, 110.3, 110.2, 79.6, 58.6, 30.0, 29.0, 23.2, 23.0; MS (ES+) m/z 292.0 (M+1).
