ChemicalBook CAS DataBase List 2-Chloro-4-bromoacetophenone

2-Chloro-4-bromoacetophenone synthesis

6synthesis methods

Product Name:2-Chloro-4-bromoacetophenone
CAS Number:252561-81-2
Molecular formula:C8H6BrClO
Molecular Weight:233.49

Benzamide, 4-bromo-2-chloro-N-methoxy-N-methyl-

875306-64-2

252561-81-2

Step 6-J: Methylmagnesium bromide (44 mL, 61.6 mmol, 1.4 M in tetrahydrofuran) was slowly added dropwise to tetrahydrofuran (50 mL) at -78 °C. Subsequently, a solution consisting of 4-bromo-2-chloro-N-methoxy-N-methylbenzamide (3.52 g, 12.7 mmol, from Step 6-I) dissolved in tetrahydrofuran (30 mL) was added. The reaction mixture was stirred at -78°C for 45 minutes, then brought to room temperature and continued stirring for 1.5 hours. After completion of the reaction, the mixture was extracted with ethyl acetate (3 times), the organic phases were combined, washed with brine, dried over anhydrous sodium sulfate, filtered and concentrated in vacuum. The crude product was purified by recrystallization (solvent: ethyl acetate/hexane) to afford 1-(4-bromo-2-chlorophenyl)ethanone as a white solid (1.1 g, 37% yield).

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Yield: 86%

Reaction Conditions:

in tetrahydrofuran at 8; for 6 h;

Steps:

21.2 2. Synthesis of 1-(4-bromo-2-chlorophenyl)ethan-1-one
To a solution of 4-bromo-2-chloro-N-methoxy-N-methylbenzamide (5.6 g, 20 mmol, 1 eq.) in THF (80 mL) was added MeMgBr (3 M, 10 mL, 30 mmol, 1.5 eq.) at 8 °C. The reaction mixture was stirred at 8 °C for 6 h and then was concentrated in vacuo. The residue was dissolved in EtOAc (100 mL) and was poured into saturated aqueous NH4Cl solution (200 mL). The layers were separated and the aqueous layer was extracted with EtOAc (100 mL). The combined organic extracts were dried (Na2SO4), filtered, and concentrated in vacuo to give 1-(4- bromo-2-chlorophenyl)ethan-1-one as a light brown solid (4 g, yield: 86%), which was carried forward without further purification. 1H NMR: (400 MHz, CDCl3) d: 7.60 (s, 1H), 7.48-7.43 (m, 2H), 2.63 (s, 3H)

References:

BIOGEN MA INC.;HOPKINS, Brian, T.;MA, Bin;PRINCE, Robin;MARX, Isaac;SCHULZ, Jürgen;NEVALAINEN, Marta WO2020/232330, 2020, A1 Location in patent:Page/Page column 98; 99

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References