Reaction Steps
Following the procedure as described in EXAMPLE 8 and making non-critical variations using 6,7-dihydrospiro[benzo[1,2-b:4,5-b′]difuran-3,3′-indol]-2′(1′H)-one to replace spiro[furo[2,3-f][1,3]benzodioxole-7,3′-indol]-2′(1′H)-one, and (S)-(1,4-dioxan-2-yl)methyl 4-methylbenzenesulfonate to replace (R)-(1,4-dioxan-2-yl)methyl 4-methylbenzenesulfonate, 1′-[(2R)-1,4-dioxan-2-ylmethyl]-6,7-dihydrospiro[benzo[1,2-b:4,5-b′]difuran-3,3′-indol]-2′(1′H)-one was obtained (97%) as a colorless solid: mp 162-164° C. (diethyl ether/hexanes); 1H NMR (300 MHz, CDCl3) (diastereomers) δ 7.302, 7.298 (ddd, J=7.8, 7.7, 1.3 Hz, 1H), 7.17-7.14 (m, 1H), 7.07-7.02 (m, 2H), 6.79 (s, 1H), 6.12, 6.09 (s, 1H), 4.91, 4.90 (d, J=8.9 Hz, 1H), 4.66, 4.65 (d, J=8.9 Hz, 1H), 4.48 (t, J=8.7 Hz, 2H), 3.98-3.78 (m, 4H), 3.75-3.55 (m, 4H), 3.45-3.37 (m, 1H), 3.14 (t, J=8.7 Hz, 2H); 13C NMR (75 MHz, CDCl3) (diastereomers) δ177.9, 177.7, 155.1, 155.0, 154.92, 154.88, 142.8, 142.7, 132.3, 132.2, 128.94, 128.89, 128.84, 128.80, 127.8, 127.7, 123.9, 123.8, 123.5, 109.6, 109.4, 107.19, 107.16, 104.0, 103.9, 80.0, 79.9, 73.3, 71.7, 69.4, 69.2, 66.8, 66.7, 66.52, 66.48, 58.46, 58.43, 41.9, 41.8, 30.4; MS (ES+) m/z 380.0 (M+1).
