4-AMINO-2-CHLOROPYRIDINE, N-BOC PROTECTED 98

2-[4-(2-Carboxyethy1)phenyl]-4-(3-heptyl-1- methylureido)pyridini\3m acetate; a. tert-Butyl (2-chlox:opyrlcL-4-yl)carbamate; 1.69 g (7.78 mmol, 1 eq) of tert-butyl dicarbonate dissolved in 50 ml of dichloromethane, in the presence of 95 mg of dimethylaminopyridine, are added to a solution of 1 g (7.78 mmol, 1 eq) of 4-amino-2-chloropyridine in 30 mL of dichloromethane in EPO StepA; ci 1) NaHMDS N T) HGF0C20 l l l 9\NH2 NHBoc the c : 2 [0073] To A solution containing 4-amino-2-chloropyridine (3. 05 g, 23. 72 mmol) in THF (24 ML) was added sodium bis (TRIMETHYLYSILYL) amide (47. 45 mmol) and stirred at room temperature for 30 minutes. To this solution was added BOC20 (23. 72 mmol) and the gelatinous mixture was stirred overnight. The reaction was diluted with water and extracted with ETOAC. The combined organic phase was washed with water and brine and dried over NA2S04 and concentrated to yield 4. 17 G (77percent). M+H+ (230).A mixture of 4-amino-2-chloropyridine (193 mg, 1.50 mmol), di-tert-butyl-di- carbonate (393 mg, 1.80 mmol) and 4-dimethylaminopyridine (1.8 mg, 0.02 mmol) in acetonitrile (5 mL) was stirred at room temperature for 18 hours. This mixture was concentrated under reduced pressure. The residue was purified by column chroma- tography on silica-gel (hexane/ethyl acetate, 20: 1) to give tert-butyl (2-chloropyridin- 4-YL) carbamate (250 mg, 73percent).