Reaction Steps
Following the procedure as described in EXAMPLE 4 and making non-critical variations using (R)-(tetrahydrofuran-2-yl)methyl 4-methylbenzenesulfonate to replace 2-(bromomethyl)tetrahydro-2H-pyran, and 5′,6′,7′,8′-tetrahydrospiro[indole-3,3′-naphtho[2,3-b]furan]-2(1′H)-one to replace 5,6-dihydrospiro[benzo[1,2-b:5,4-b′]difuran-3,3′-indol]-2″(1′H)-one, 1-[(2R)-tetrahydrofuran-2-ylmethyl]-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 139-141° C.; 1H NMR (300 MHz, CDCl3) δ 7.32-7.27 (m, 1H), 7.15-7.01 (m, 3H), 6.66 (s, 1H), 6.41 (s, 1H), 4.88 (dd, J=8.9, 0.9 Hz, 1H), 4.63 (dd, J=8.9, 2.5 Hz, 1H), 4.32-4.24 (m, 1H), 4.00-3.69 (m, 4H), 2.75-2.71 (m, 2H), 2.54 (br s, 2H), 2.10-1.86 (m, 3H), 1.78-1.69 (m, 5H); 13C NMR (75 MHz, CDCl3) δ178.0, 158.6, 142.9, 138.8, 132.4, 130.0, 128.6, 126.5, 123.6, 123.4, 123.2, 110.1, 109.5 79.7, 76.9, 68.2, 57.9, 44.6, 29.9, 29.2, 29.0, 25.6, 23.2, 23.0; MS (ES+) m/z 375.9 (M+1).
