Reaction Steps
Following the procedure as described in EXAMPLE 4 and making non-critical variations using 4′-chloro-5,6-dihydrospiro[benzo[1,2-b:5,4-b′]difuran-3,3′-indol]-2′(1′H)-one to replace 5,6-dihydrospiro[benzo[1,2-b:5,4-b′]difuran-3,3′-indol]-2″(1′H)-one, and (R)-(tetrahydrofuran-2-yl)methyl 4-methylbenzenesulfonate to replace 2-(bromomethyl)tetrahydro-2H-pyran, 4′-chloro-1′-[(2R)-tetrahydrofuran-2-ylmethyl]-5,6-dihydrospiro[benzo[1,2-b:5,4-b′]difuran-3,3′-indol]-2′(1′H)-one was obtained (80%) as a colorless solid: mp 78-82° C.; 1H NMR (300 MHz, DMSO-d6) δ7.32-7.09 (m, 1H), 7.05-6.92 (m, 1H), 6.44 (s, 1H), 6.35 (s, 1H), 4.96 (dd, J=9.1, 1.1 Hz, 1H), 4.85 (d, J=9.1 Hz, 1H), 4.51 (t, J=8.7 Hz, 1H), 4.31-4.16 (m, 1H), 4.00-3.59 (m, 1H), 2.98 (t, J=8.6 Hz, 1H), 2.12-1.80 (m, 1H), 1.76-1.61 (m, 1H); 13C NMR (75 MHz, DMSO-d6) δ178.0 (2), 162.1 (2), 162.0, 144.7, 131.1 (2), 129.8 (2), 128.7 (2), 123.9, 119.4 (2), 118.4 (2), 117.5 (2), 108.1 (2), 92.9, 77.5, 76.9 (2), 72.3, 68.2 (2), 58.1 (2), 44.9 (2), 29.1 (2), 29.0 (2), 25.6 (2); MS (ES+) m/z 397.9 (M+1), 399.9 (M+1).
