1,3-Dibromo-5,5-dimethylhydantoin → tert-butyl N-[6-(bromomethyl)-2-pyridyl]-N-tert-butoxycarbonyl-carbamate

Participants

Reaction Conditions

Reaction Steps

To 102.8 g (334 mmol) of t-butyl t-butoxycarbonyl-(6-methyl-pyridin-2-yl)-carbamate were added 10.95 g (20 mol %) of 2,2′-azobisisobutyronitrile and 1,330 ml of chlorobenzene. To the resulting mixture was added 95.31 g of 1,3-dibromo-5,5-dimethylhydantoin, and the temperature of the mixture was then raised to 90° C. at a rate of 2° C./minute and held at the temperature for one hour. Subsequently, the reaction mixture was cooled to 20° C., the precipitate was filtered off, and the volume of chlorobenzene was reduced by half by distillation. The thus obtained residue was cooled to 10° C. or lower, and then 46.03 g (43 ml) of diisopropylethylamine and 43.08 g (58 ml) of diethyl phosphite were added thereto, followed by aging the mixture at room temperature for 16.5 hours. Following confirmation by performing thin-layer chromatography that the raw materials had disappeared, the reaction mixture was washed with 300 ml of 3 N hydrochloric acid, and then further washed with 500 ml of a saturated saline solution. The resulting solution was then dried over anhydrous magnesium sulfate and filtered, yielding a solution of 2-bis(t-butoxycarbonyl)amino-6-bromomethyl-pyridine.

Provenance & Evidence