Reaction Steps
Following the procedure as described in EXAMPLE 8 and making non-critical variations using 3-methylspiro[furo[2,3-f][1,3]benzoxazole-7,3′-indole]-2,2′(1′H,3H)-dione to replace spiro[furo[2,3-f][1,3]benzodioxole-7,3′-indol]-2′(1′H)-one, and (R)-(tetrahydrofuran-2-yl)methyl 4-methylbenzenesulfonate to replace (R)-(1,4-dioxan-2-yl)methyl 4-methyl benzenesulfonate, 3-methyl-1′-(((R)-tetrahydrofuran-2-yl)methyl)-2H-spiro[benzofuro[6,5-d]oxazole-7,3′-indoline]-2,2′(3H,6H)-dione was obtained (69%) as a colorless solid: mp 186-187° C. (diethyl ether); 1H NMR (300 MHz, DMSO-d6) δ7.36-7.29 (m, 1H), 7.23 (d, J=8.2 Hz, 1H), 7.14 (d, J=8.2 Hz, 1H), 7.06-7.02 (m, 2H), 6.63 (d, J=6.9 Hz, 1H), 4.85-4.73 (m, 2H), 4.24-4.16 (m, 1H), 3.81-3.59 (m, 4H), 3.31 (s, 3H), 2.00-1.75 (m, 3H), 1.69-1.55 (m, 1H); 13C NMR (75 MHz, DMSO-d6) δ177.2, 157.3, 154.9, 143.4, 136.6, 133.3, 131.9, 129.3, 123.9, 123.3, 122.3, 110.2, 105.0, 92.9, 80.0, 76.1, 67.7, 57.7, 44.3, 29.1, 28.6, 25.5; MS (ES+) m/z 392.7 (M+1).
