反应详情

Potassium t-butoxide (2.6 g, 23 mmol) was dissolved in DMSO (10 mL) and to this solution was added ethyl 3-tert-butyl-1H-pyrazole-5-carboxylate (4.5 g, 23 mmol) in small portions and stirred under Ar for 15 min. To this solution was added t-butyl-bromoacetate (5.4 g, 28 mmol) slowly at 0° C. with stirring for 45 min at RT. Sat. NH4Cl solution was added and product was extracted with ethyl acetate (3×50 mL). The combined organic layers were washed with brine, dried (Na2SO4) and concentrated to afford (7.0 g) coupled product as a pasty mass. The above pasty mass was dissolved in TFA (10 mL) and stirred for 3 h at RT. Solvents were removed, water (100 mL) was added and product was extracted with DCM (3×50 ml). The combined organic extracts were washed with brine solution, dried (Na2SO4) and concentrated to yield 2-(3-tert-butyl-5-(ethoxycarbonyl)-1H-pyrazol-1-yl)acetic acid (5.8 gm, 100%) as a pasty mass. 1H NMR (400 MHz, Acetone-d6): δ 6.78 (s, 1H), 5.25 (s, 2H), 4.30 (q, J=7.2 Hz, 2H), 1.35-1.30 (m, 12H); MS (ESI) m/z: 255.2 (M+H+).

1. stirringwith stirring for 45 min at RT
2. extractionproduct was extracted with ethyl acetate (3×50 mL)
3. washThe combined organic layers were washed with brine
4. dry with materialdried (Na2SO4)
5. concentrationconcentrated
6. customto afford (7.0 g)
7. stirringstirred for 3 h at RT
8. customSolvents were removed
9. additionwater (100 mL) was added
10. extractionproduct was extracted with DCM (3×50 ml)
11. washThe combined organic extracts were washed with brine solution
12. dry with materialdried (Na2SO4)
13. concentrationconcentrated