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2-Bromo-1-cyclopropylethanone is an intermediate used to prepare pyrrolo[2,1-f]purine-2,4-dione and imidazo[2,1-f]purine-2,4-dione derivatives as potent and selective human A3 adenosine receptor antagonists. It is also used to synthesize indolizine derivatives incorporating a cyclopropylcarbonyl group against Hep-G2 cancer cell line.

The general procedure for the synthesis of 1-cyclopropyl-2-bromoacetophenone from cyclopropylmethyl ketone was as follows: a methanol (MeOH, 100 mL) solution of cyclopropylmethyl ketone (20.7 mL, 220 mmol) was treated with bromine (11.3 mL, 220 mmol) at -5 °C and the reaction lasted for 2 hours. Subsequently, 50 mL of water was added to the reaction mixture and the reaction system was slowly warmed to room temperature and left to stand overnight. After completion of the reaction, the mixture was diluted with 150 mL of water and extracted with ether. The organic phase was separated, washed with sodium bicarbonate (NaHCO3) solution, dried over anhydrous sodium sulfate (Na2SO4), and concentrated to remove the solvent to give the light yellow oily product 1-cyclopropyl-2-bromoacetophenone (35 g, 99% yield). The structure of the product was confirmed by 1H NMR (CDCl3): δ 0.91-1.02 (m, 2H), 1.03-1.16 (m, 2H), 2.08-2.20 (m, 1H), 4.02 (s, 2H).

[1] Patent: US2010/196321, 2010, A1. Location in patent: Page/Page column 22
[2] Patent: WO2013/184734, 2013, A1. Location in patent: Paragraph 00299; 00300
[3] Synlett, 2010, # 6, p. 873 - 876
[4] Patent: WO2010/96395, 2010, A1. Location in patent: Page/Page column 34
[5] Patent: WO2015/76800, 2015, A1. Location in patent: Page/Page column 318