Reaction Steps
Following the procedure as described in EXAMPLE 4 and making non-critical variations using 1-methylspiro[furo[3,2-f][1,3]benzoxazole-7,3′-indole]-2,2′(1H,1′H)-dione to replace 5,6-dihydrospiro[benzo[1,2-b:5,4-b′]difuran-3,3′-indol]-2″(1H)-one, and (R)-(tetrahydrofuran-2-yl)methyl 4-methylbenzenesulfonate to replace 2-(bromomethyl)tetrahydro-2H-pyran, 1-methyl-1′-[(2R)-tetrahydrofuran-2-ylmethyl]spiro[furo[3,2-f][1,3]benzoxazole-7,3′-indole]-2,2′(1H,1′H)-dione was obtained (32%) as a colorless solid: mp>250° C. (toluene/hexanes); 1H NMR (300 MHz, CDCl3) δ7.38-7.29 (m, 1H), 7.17-7.03 (m, 3H), 6.90-6.85 (m, 1H), 6.40-6.28 (m, 1H), 4.99-4.92 (m, 1H), 4.75-4.67 (m, 1H), 4.36-4.25 (m, 1H), 4.01-3.67 (m, 4H), 3.25-3.21 (m, 3H), 2.14-1.85 (m, 3H), 1.79-1.65 (m, 1H); 13C NMR (75 MHz, CDCl3) δ177.6, 157.0, 156.9, 155.0, 143.5 (2C), 143.1, 142.6, 132.2, 131.9, 129.3, 129.2, 126.2, 124.1, 123.8, 123.6, 109.8, 109.8, 103.1, 103.0, 94.7 (2C), 80.5, 80.4, 77.1, 76.3, 68.4, 68.2, 58.2 (2C), 45.0, 44.7, 29.3, 29.2, 28.3, 28.2, 25.7; MS (ES+) m/z 393.0 (M+1).
