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ChemicalBook CAS DataBase List ETHYL 3-(4-BROMOPHENYL)-1-METHYL-1H-PYRAZOLE-5-CARBOXYLATE

ETHYL 3-(4-BROMOPHENYL)-1-METHYL-1H-PYRAZOLE-5-CARBOXYLATE synthesis

3synthesis methods
-

Yield:618070-50-1 40% ,852815-31-7 37%

Reaction Conditions:

in ethanol at 90; for 2 h;

Steps:



Intermediate 49 ethvl 3- (4-bromophenvi)-l-methyl-1 H-pyrazole-5-carboxylate Intermediate 50 ethyl 5- (4-bromophenvl)-1-methvl-1 H-pvrazole-3-carboxvlate To a hot (70 C) solution of intermediate 48 (31.4 g, 0.105 mol) in 500 mL of ethanol was added two volumes of methylhydrazine (5.85 mL, 0. 11mol), then it was stirred at 90 C for 2h. The resulting mixture was concentrated to dryness, dissolved in ethylacetate, washed with HCI (1N), brine, dried onNa2SO4 and evaporated to dryness, then purified by flash chromatography (Cyclohexane/ethylacetate 90/10 to 70/30) to obtain two products, intermediate 49 first eluted and intermediate 50: *The first was triturated in heptane to give crystals : 12.9g of-Intermediate 49. Yield : 40% 1H NMR(CDCl3) 8 : 7.49 (d, 2H); 7.34 (d, 2H); 6.91 (s, 1H); 4.19 (quad, 2H); 4.03 (s, 3H); 1.22 (t, 3H) *The second (12. 1g): - Intermediate 50. Yield : 37% 1H NMR(CDCI3)d : 7.55 (d, 2H); 7.22 (d, 2H); 6.78 (s, 1H); 4.36 (quad, 2H); 3.87 (s, 3H); 1.34 (t, 3H)

References:

WO2005/49578,2005,A1 Location in patent:Page/Page column 63-64