nitro spiro cyclopentane 1 3 u2032 indolin 2 u2032 one a mertens et al j med chem 1987 30 8 1279 1287 the title compound was obtained as light yellow solid 1 h nmr cdcl 3 400 mhz u03b4 ppm 8 84 8 82 m 2h 7 90 bs 1h 7 75 7 73 m 2h 7 50 m 1h 7 19 7 16 m 1h 7 04 7 00 m 1h 3 24 s 3h 2 20 1 80 m 8h prepared in analogy to example 1b from nicotinic acid and 6 amino 1 3 3 trimethylindolin 2 one w von der saal et al j med chem 1989 32 7 1481 1491 the title compound was obtained as light yellow solid 1 h nmr cdcl 3 400 mhz u03b4 ppm 9 12 9 11 m 1h 8 81 8 79 m 1h 8 25 8 21 m 1h 7 96 bs 1h 7 56 7 55 m 1h 7 49 7 45 m 1h 7 20 7 17 m 1h 7 06 7 02 m 1h 3 25 s 3h 1 38 s 6h prepared in analogy to example 1b from 6 amino 1 3 3 trimethylindolin 2 one w von der saal et al j med chem 1989 32 7 1481 1491 the title compound was obtained as light brown solid 1 h nmr cdcl 3 400 mhz u03b4 ppm 8 70 8 68 m 1h 7 88 bs 1h 7 59 7 54 m 1h 7 51 7 49 m 1h 7 20 7 17 m 1h 7 04 7 01 m 1h 3 24 s 3h 2 68 s 3h 1 37 s 6h prepared in analogy to example 20d 37b 37c and 2 from 6 chloro.