Reacción #79057

Ecuación de reacción

2-bromo-3-cyano-4,6-diaminopyridine

KOAc

benzene

NaOH

→

3-cyano-4,6-diaminopyridine

Rendimiento 69.0%

Disolventes

THF MeOH

HCl

water

Condiciones de reacción

Tratamiento posterior

1. 1
   FiltraciónFiltration over celite
2. 2
   Lavadowashing with THF/MeOH and removal of the solvent
3. 3
   Otrogives a solid, which

Procedimiento

Crude 2-bromo-3-cyano-4,6-diaminopyridine [(W. J. Middleton, U.S. Pat. No. 2,790,806 (Apr. 30, 1957), Du Pont; Chem. Abst. 51:P14829 (1957), see also next experimental] (15.1 g, 0.071 mole) is hydrogenated in THF/MeOH (200 mL, 2:1) containing KOAc (7.0 g, 0.071 mole) and 5% Pd/C (4 g) at 55 p.s.i. and 20° C. for 7 days. Filtration over celite, washing with THF/MeOH and removal of the solvent gives a solid, which is dissolved in dilute HCl and water. Adjustment of the solution pH to 10 (conc. NaOH) and cooling gives 3-cyano-4,6-diaminopyridine (6.58 g, 69%) as a yellow solid, mp 197-198° C. [Metzger, R.; Oberdorfer, J.; Schwager, C.; Thielecke, W.; Boldt, P. Liebigs Ann. Chem. 1980, 946-953 record mp (benzene) 205° C.]. Extraction of the remaining liquor with EtOAc (4×200 mL) gives further product (2.12 g, 22%). 1H NMR (DMSO) δ 7.91 (1H, s), 6.26, 6.24 (2H, 2H, brs), 5.63 (1H, s)

Fuente