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ChemicalBook CAS DataBase List 3-BROMO-PYRAZOLO[1,5-A]PYRIDINE
5910-12-3

3-BROMO-PYRAZOLO[1,5-A]PYRIDINE synthesis

2synthesis methods
Pyrazolo[1,5-a]pyridine-3-carboxylic acid

16205-46-2

3-BROMO-PYRAZOLO[1,5-A]PYRIDINE

5910-12-3

The general procedure for the synthesis of 3-bromopyrazolo[1,5-a]pyridine-3-carboxylic acid from pyrazolo[1,5-a]pyridine was as follows: N-bromosuccinimide (3.06 g, 17.22 mmol) and sodium bicarbonate (4.34 g, 51.66 mmol) were sequentially added to a N,N-dimethylformamide (40 mL) solution of pyrazolo[1,5-a]pyridine-3-carboxylic acid (2.81 g, 17.22 mmol) in a solution of N,N-dimethylformamide (40 mL). The reaction mixture was stirred at room temperature for 4 h and then poured into water (100 mL). The resulting suspension was extracted twice with ethyl acetate and the organic layers were combined and dried over anhydrous magnesium sulfate. After filtration, the solvent was removed by concentration under reduced pressure. The crude product was purified by fast column chromatography (eluent: hexane/ethyl acetate = 8:2) to afford the target product 3-bromopyrazolo[1,5-a]pyridine (2.58 g, 76% yield). Mass spectrum (LRMS) showed m/z: 197 ([M+1]+). 1H-NMR (250 MHz, CDCl3) δ: 6.8 (t, 1H), 7.2 (t, 1H), 7.5 (d, 1H), 7.9 (s, 1H), 8.4 (d, 1H).

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Yield: 76%

Reaction Conditions:

with N-Bromosuccinimide;sodium hydrogencarbonate in N,N-dimethyl-formamide at 20; for 4 h;

Steps:

22.c
N-Bromosuccinimide (3.06 g, 17.22 mmol) and sodium hydrogen carbonate (4.34 g, 51.66 mmol) were added to a solution of pyrazolo[1 ,5-a]pyridine-3-carboxylic acid (Preparation 22b, 2.81 g, 17.22 mmol) in A/.A/'-dimethylformamide (40 mL) and the resulting mixture was stirred at room temperature for 4h before being poured over 100 mL of water. The resulting suspension was extracted twice with ethyl acetate and the combined organic layers were dried over magnesium sulphate, filtered and the solvent was evaporated. The crude product was purified by flash chromatography (8:2 hexane/ethyl acetate) to yield the title compound (2.58 g, 76%).LRMS (m/z): 197 (M+1)+.1H-NMR δ (250 MHz, CDCI3): 6.8 (t, 1 H), 7.2 (t, 1 H), 7.5 (d, 1 H), 7.9 (s, 1 H), 8.4 (d, 1 H).

References:

ALMIRALL, S.A.;BACH TAŇA, Jordi;PAGES SANTACANA, Lluis, Miquel;TALTAVULL MOLL, Joan;EASTWOOD, Paul, Robert;GONZALEZ RODRIGUES, Jacob;GIULIO MATASSA, Victor WO2011/101161, 2011, A1 Location in patent:Page/Page column 99

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