Reaction Steps
Following the procedure as described in EXAMPLE 4 and making non-critical variations using 4′-bromo-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′-bromo-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 (75%) as a colorless solid: mp 137-141° C.; 1H NMR (300 MHz, DMSO-d6) (diastereomers) δ7.30-7.10 (m, 3H), 6.42-6.37 (m, 1H), 6.32 (s, 1H), 4.88 (d, J=9.63 Hz, 1H), 4.70-4.63 (m, 1H), 4.46 (t, J=8.6 Hz, 2H), 4.18-4.05 (m, 1H), 3.85-3.52 (m, 4H), 2.93 (t, J=8.5 Hz, 2H), 2.01-1.67 (m, 3H), 1.64-1.49 (m, 1H); 13C NMR (75 MHz, DMSO-d6) δ177.5 (2), 162.2, 161.8, 145.7, 130.9, 130.2 (2), 126.6, 119.9 (2), 119.0 (2), 118.9 (2), 118.1, 92.5, 77.5, 76.3, 76.1, 72.5, 67.7 (2), 65.4, 58.7, 44.5, 29.0 (2), 28.7, 25.5; MS (ES+) m/z 443.9 (M+1), 445.9 (M+1).
