ChemicalBook CAS DataBase List Methyl 6-bromo-3-oxo-3,4-dihydropyrazine-2-carboxylate

Methyl 6-bromo-3-oxo-3,4-dihydropyrazine-2-carboxylate synthesis

5synthesis methods

Product Name:Methyl 6-bromo-3-oxo-3,4-dihydropyrazine-2-carboxylate
CAS Number:21874-61-3
Molecular formula:C6H5BrN2O3
Molecular Weight:233.02

6966-01-4 Synthesis

Methyl 3-amino-6-bromopyrazine-2-carboxylate

6966-01-4
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Methyl 6-bromo-3-oxo-3,4-dihydropyrazine-2-carboxylate

21874-61-3
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Yield:21874-61-3 92.7%

Reaction Conditions:

Stage #1: methyl 3-amino-6-bromopyrazine-2-carboxylatewith sulfuric acid;sodium nitrite at -5 - 25; for 2 h;
Stage #2: with water for 1.5 h;

Steps:

Preparation of methyl 3-hydroxy-6-bromopyrazine-2-carboxylate (4) (Furuta and Egawa 2000)

Methyl 3-amino-6-bromopyrazine-2-carboxylate (10 g,1 eq) was suspended in concentrated H2SO4 (40 mL), andthen, NaNO2 (5.96 g, 2 eq) was added in batches at -5 to0 C, after which the reaction was stirred at 25 C for 2 huntil the solid was all dissolved. Then, the reaction solutionwas poured into ice water (400 mL) and vigorously stirredfor 1.5 h. Afterward, the solution was extracted with ethylacetate (3 9 50 mL). The organic layer was combined andwashed with water (3 9 30 mL). Then, it was dried withanhydrous Na2SO4 for 5 h and filtered to remove the dryingagent. The ethyl acetate was removed by distillation under reduced pressure to obtain methyl 3-hydroxy-6-bromopyrazine-2-carboxylate (9.3 g, 92.7%) (TLC,EA:MeOH = 1:1, v/v, Rf = 0.77).Methyl 3-hydroxy-6-bromopyrazine-2-carboxylate(4)Yield: 92.7%, gray solid, m.p.: 120-122 C (Lit.120.5-121.5 C) (Caldwell et al. 2012). 1H-NMR(400 MHz, DMSO-d6): d 8.40 (s, 1H), 3.85 (s, 3H). 13CNMR(101 MHz, DMSO-d6): d 163.20, 157.11, 143.89,134.81, 122.06, 52.43. MS (EI): m/z = 233.0 (M?, Br79,40), 235.0 (M?, Br81, 40), 202.0 (M?, -OCH3, Br79, 45),204.0 (M?, -OCH3, Br81, 25), 174.0 (M?, -COOCH3,Br79, 100), 176.0 (M?, -COOCH3, Br79, 60).

References:

Liu, Feng-Liang;Li, Cui-Qin;Xiang, Hao-Yue;Feng, Si [Chemical Papers,2017,vol. 71,# 11,p. 2153 - 2158]

27825-20-3 Synthesis