6-Bromoimidazo[1,2-a]pyridine

(1)To a solution of 5-bromopyridin-2-amine (10.0 g, 57.7 mmol) in EtOH/HThe scheme above describes the synthesis of a compound of the invention. A substituted pyridine such as compound 1-1 is reacted with 2-chloroacetaldehyde, resulting in the halogenated imidazopyridine compound 1-2.j0554] The scheme above describes the synthesis of a compound of the invention. A substituted pyridine such as compound 1-1 is reacted with 2-chloroacetaldehyde, resulting in the halogenated imidazopyridine compound 1-2. Compound 1-2 is coupled to a benzoxazolyl boronic acid ester in Suzuki conditions to produce compound 1-4. Further derivatization of compound 1-4 using, for example, NBS, DMF results in halogenation of the imidazopyridine moiety, which is then further reacted in an additional Suzuki coupling using pyridine boronic acid to result in compound 1-6.2-Amino-5-bromopyridine (Aldrich, 18.8 g, 108.7 mmol), chloroacetaldehyde (34 mL of 50percent solution in water, 217.4 mmol), NaHCOReflux a solution OF 2-AMINO-5-BROMO-PYRIDINE (Maybridge; 1.0 g, 5.78 mmol), 50percent aqueous chloroacetaldehyde (2 mL, 12.7 mmol) in acetonitrile (100 mL) for 14 h. Dilute the reaction with saturated aqueous sodium bicarbonate and extract into ethyl acetate. Flash chromatography using appropriate ethyl acetate/hexane mixtures gives 0.95 g (83percent) of the subtitled compound as a tan solid. MS (electrospray, m/z) 196.7, 198.7 (M+1). 1H NMR (400 MHz, DMSO-d6) 8 8.9 (d, J= 1. 5 Hz, 1H), 7.90 (s, 1H), 7.58 (d, J = 1.5 Hz, 1H), 7.53 (d, J = 9. 2 HZ, 1H), 7.29 (dd, J = 9. 2, 2 HZ, 1H).To a stirred solution of 5-bromo-pyridin-2-amine (5 g, 28.9 mmol) and sodium acetate (4.0 g, 48.76 mmol) in 100 mL of 60 percent ethanol in water, was added a refluxed solution of sodium acetate (2.0 g, 24.38 mmol) followed by 2-chloro-1 , 1 -dimethoxyethane (6.66 g, 53.5 mmol) in concentrated hydrochloric acid (1 .0 mL) in water (6 mL) and the reaction mass was refluxed for 2.5 h. The solvent was removed, residue obtained was diluted with cold water and pH adjusted to neutral (~7) with saturated sodium bicarbonate solution. The reaction mixture was extracted with ethyl acetate (2x100 mL), washed with water (2x100 mL) and brine (2x100 mL) and dried over anhydrous sodium sulphate. The crude material obtained was purified by trituration using 2 percent ethyl acetate in petroleum ether. Yield: 3.6 g (64.28 percent);