902835-93-2

16867-03-1

24424-99-5

902835-93-2

General procedure for the synthesis of tert-butyl (3-hydroxypyridin-2-yl)carbamate from 2-amino-3-hydroxypyridine and di-tert-butyl dicarbonate: 2-amino-3-hydroxypyridine (1 mmol) was added to a reaction vial containing a magnetic stirrer, followed by the addition of guanidine hydrochloride (15 mol%) and di-tert-butyl dicarbonate (1.2 mmol) to an ethanol (1 mL) solution. The reaction mixture was stirred at 35-40 °C until the reaction was complete (monitored by TLC or GC). Upon completion of the reaction, the ethanol is evaporated under vacuum and the residue is washed with water to remove the catalyst or dissolved in dichloromethane (or ethyl acetate) and the catalyst is separated by filtration. If an organic solvent is used for post-treatment, evaporation of the organic solvent gives an almost pure product. If excess di-tert-butyl dicarbonate has been used, the product can be washed with petroleum ether or hexane to recover the residual di-tert-butyl dicarbonate. If necessary, the product can be further purified by crystallization (using a solvent mixture of hexane and dichloromethane, or ethyl ether and petroleum ether) or silica gel column chromatography (using ethyl acetate-hexane (1:6) as eluent).