4-Cyanophenylhydrazine Hydrochloride → 2-(4-Cyanophenyl)-3-cyclopentyl-2,3,3a,4-tetrahydrochromeno[4,3-c]pyrazole-7-carboxylic acid

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Reaction Steps

The title compound was prepared from methyl 3-(cyclopentylmethylene)-4-oxochroman-7-carboxylate; Preparation 31 (286 mg, 1.0 mmol) and 4-hydrazinylbenzonitrile hydrochloride (Aldrich; 254 mg, 1.5 mmol) according to Method B and Method C. 2-(4-Cyanophenyl)-3-cyclopentyl-2,3,3a,4-tetrahydrochromeno[4,3-c]pyrazole-7-carboxylic acid was obtained (yellow solid, 142 mg, 0.367 mmol, 37% yield). The title compound was largely present as (±)-(3RS,3aSR)-2-(4-cyanophenyl)-3-cyclopentyl-2,3,3a,4-tetrahydrochromeno[4,3-c]pyrazole-7-carboxylic acid. 1H NMR (400 MHz, DMSO-d6) δ ppm 13.16 (br. s., 1H), 7.93 (d, J=7.8 Hz, 1H), 7.53-7.66 (m, 3H), 7.46 (s, 1H), 7.27 (d, J=9.0 Hz, 2H), 4.90 (dd, J=9.4, 7.0 Hz, 1H), 4.77 (dd, J=10.4, 5.7 Hz, 1H), 4.30 (dd, J=12.7, 10.7 Hz, 1H), 3.98 (ddd, J=12.9, 9.8, 5.9 Hz, 1H), 2.02-2.16 (m, 1H), 1.56-1.67 (m, 1H), 1.43-1.55 (m, 3H), 1.29-1.43 (m, 2H), 1.13-1.29 (m, 2H). ES-MS m/z 388 (M+H).

Provenance & Evidence