Hydrazine hydrate (1:1) → Ethyl 6-methyl-1,4,5,6-tetrahydrocyclopenta[c]pyrazole-3-carboxylate

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Reaction Steps

Hydrazine hydrate (0.101 mL, 2.05 mmol) was added to a stirring room temperature solution of 4 (0.4055 g, 2.05 mmol) in EtOH (2.0 mL, 1 M) under N2. The reaction was then heated to reflux until judged complete by TLC. The reaction was concentrated and purified by silica gel chromatography (Combiflash column, 96:4 Hexanes:2N NH3 in EtOH): Only pure fractions were combined and concentrated to obtain 0.2003 g (50.4%) of 5. 1H (CDCl3, 400 MHz): δ 9.55 (1H, broad s), 4.35 (2H, q, J=7.1 Hz), 3.26-3.16 (1H, m), 2.89-2.63 (3H, m), 2.09-1.98 (1H, m), 1.37 (3H, t, J=7.2 Hz), 1.30 (3H, d, J=6.9 Hz) ppm. Partial 13C (CDCl3, 100 MHz): δ 128.67, 61.32, 39.73, 32.64, 22.94, 19.62, 14.52 ppm. HPLC: 8.901 min.

Provenance & Evidence