Ethyl 5-isopropylpyrazole-3-carboxylate

Uses

Ethyl 3-isopropyl-1H-pyrazole-5-carboxylate,

Synthesis

General procedure for the synthesis of ethyl 5-isopropylpyrazole-3-carboxylate from ethyl 2,4-dioxo-5-methyl-hexanoate: a mixture of ethyl 2,4-dioxo-5-methyl-hexanoate (1 g, 5.37 mmol) and hydrazine hydrate (10.7 mmol, 9.64 mol/L) in ethanol (20 mL) was stirred for 1 hr at 75 °C under nitrogen atmosphere. After completion of the reaction, the mixture was concentrated under vacuum. The residue was purified by silica gel column chromatography using petroleum ether: ethyl acetate (2:1, v/v) as eluent to afford ethyl 5-isopropylpyrazole-3-carboxylate (0.55 g, 56% yield) as a light yellow solid. Mass spectrum (ESI, positive ion mode) m/z: 183.1 [M + H]+. 1H NMR (600 MHz, CDCl3) δ: 11.37 (br s, 1H), 6.63 (s, 1H), 4.40-4.37 (m, 2H), 3.07-3.05 (m, 1H), 1.43-1.40 (m, 3H), 1.39- 1.30 (m, 6H).

References

[1] Patent: WO2016/127859, 2016, A1. Location in patent: Paragraph 00202
[2] Patent: WO2015/165835, 2015, A1. Location in patent: Page/Page column 63; 64
[3] Bioorganic and Medicinal Chemistry Letters, 2007, vol. 17, # 20, p. 5620 - 5623
[4] Bioorganic and Medicinal Chemistry Letters, 2009, vol. 19, # 9, p. 2537 - 2541
[5] Patent: US2004/220186, 2004, A1. Location in patent: Page 18