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- 1-Hydroxy-4-iodooxindole (5): mp. 228–30°C, 300 MHz 1H-NMR (δ, d6-DMSO): 7.2–7:3(m. 1H), 6.80–6.95(m, 2H), 3.20(s, 2H), 13C NMR 168.76, 144.16, 130.90, 126.69, 125.81, 107.18, 91.97, 38.37 ppm. IR(CHCl3) 3150–2750(b), 1700, 768 cm−1. Anal, calcd. for C8H6NO2I: C, 34.9, H, 2.18, N, 5.09. Found: C, 34.96, H, 2.19, N, 5.00. Recrystalized from ethanol-water./, (b) 1-Hydroxyoxindole (6): mp. 198–202°C, 300 MHz 1H-NMR (8, δd6-DMSO): 6.85–7.05(m, 4H), 3.13(s, 2H), 13C NMR 169.84, 143.46, 127.77, 124.10, 122.25, 120.54, 107.41, 33.80 ppm. IR (CHCl3) 3500–2650(b), 1680, 915, 750 cm−1. Anal, calcd. for C8H7NO2: C, 64.4, H, 4.70, N, 9.40. Found: C, 64.13, H, 4.72, N, 9.35. Recrystalized from THF. (c) 1-Hydroxy-3-methyloxindole (7): (oil), 300 MHz 1H-NMR (δ, d6-DMSO): 7.0–7.2(m, 4H). 3.25(q, 1H), 1.42(d, 2H), 13C NMR 174.82, 141.61, 128.20, 127.07, 123.33, 123.27, 108.45, 39.24, 14.74 ppm. IR (CHCl3) 3500–2650(b), 1700, 1630, 930, 750 cm−1. (d) 4-Carboxy-1-hydroxyoxindole (8): mp. 251–53°C, 300 MHz 1H-NMR (δ, d6-DMSO): 7.35(d, 1H), 7.05(t, 1H), 6.82(d, 1H), 3.42(s, 2H), 13C NMR 169.84, 167.24, 144.15, 127.77, 126.72, 123.50, 123.07, 110.86, 35.51 ppm. IR (CHCl3) 3700–2750(b), 1730, 1680, 1250, 925, 750 cm−1. Anal, calcd. for C9H7NO4. C, 56.0, H, 3.63, N, 7.25. Found: C, 55.92, H, 3.78, N, 7.13. Recrystalized from acetone. (e) 1-Hydroxy-6-methoxyoxindole (9): mp. 170–73°C, 300 MHz 1H-NMR (δ, d6-DMSO): 6.92(d, 1H), 6.48(m, 1H), 6.40(m, 1H)3.65(s, 3H), 3.25(s, 2H), 13C NMR 170.68, 159.99, 144.69, 124.76, 112.09, 107.09, 94.83. 55.40, 33.34 ppm. IR (CHCl3) 3500–2650(b), 1700, 1650, 1240 cm−1. Anal, calcd. for C9H9NO3: C, 60.3, H, 5.02, N, 7.82. Found: C, 60.17, H, 5.14, N. 7.73. Recrystalized from ethyl acetate-hexane. (f) 1-Hydroxy-4-methyloxindole (10): mp. 202–4°C, 300 MHz 1H-NMR (δ, d6-DMSO): 7.05–7.10(m, 1H), 6.75–6.85(m, 2H), 3.35(s, 2H), 2.18(s, 3H), 13C NMR 170.15, 143.19, 133.69, 127.95, 123.77, 119.19, 105.30, 32.94, 17.90 ppm. IR (CHCl3) 3200–2650(b), 1700cm−1. Anal, calcd. for C9H9NO2: C, 66.3, H, 5.52, N, 8.59. Found: C, 66.12, H, 5.51, N, 8.55. (g) 1-Hydroxy-5-methoxyoxindolc (11): Compound is obtained as an oil which is >85% pure (as determined by 1H-NMR) by flash chromatography on silica gel (1/1 hexane-ethyl acetate), 300 MHz 1H-NMR (δ, d6-DMSO): 6.48-.78(m, 3H), 3.71(s, 3H), 3.27(s, 2H). Compound decomposes rapidly to tar. (h) 1-Hydroxy-5-methyloxindole (12): Compound is obtained as an oil which is >90% pure (as determined by 1H NMR) by flash chromatography on silica gel (1/1 hexane-ethyl acetate), 300 MHz 1H-NMR (δ, d6-DMSO): 6.45–73(m, 3H), 3.27(s, 2H), 2.25(s, 3H). Compound decomposes rapidly to tar
- Alternative procedure. This procedure is the same as above but instead of using the water displacement hydrogenation apparatus a Parr shaker apparatus was used. In this case the reaction was shaken for four hours under three atmospheres of hydrogen gas. The reaction was worked up as before and gave yields that were the same as those from the previous method for the starting materials tried