Urea → HCID 11528520, compound

Participants

Reaction Steps

A solution of Br2 (1 ml, 19.3 mmol, 1 equiv.) in DMF (5 ml) is added over 20 min to a solution of N-methoxycarbonyl-1,2-dihydropyridine 1 (2.68 g, 19.3 mmol, 1 equiv.) and of urea (2.3 g, 38.6 mmol, 3 equiv.) in a mixture of DMF (19 ml) and of CH3CN (6 ml) at ambient temperature and under argon. The reaction being complete from the end of the addition of the bromine, the reaction mixture is concentrated to dryness. The residue is dissolved in methanol (30 ml), poured onto ice-cold water (150 ml) and then filtered through a Buchner funnel. The filtrate is basified (5% Na2CO3) until a pH of greater than 10 is obtained. After extracting with dichloromethane (4×100 ml), the aqueous phase is saturated with NaCl and then reextracted with dichloromethane (4×100 ml). After drying over MgSO4 and evaporating the solvent, the solid obtained (5.94 g) is chromatographed on silica gel using dichloromethane (DCM) saturated with ammonia and then DCM saturated with NH3:MeOH, 98:2. The product is obtained in the form of a beige solid (1.9 g, 50%).

Provenance & Evidence