Reaktion #502090

Reaktionsgleichung

hydroxylamine hydrochloride

N,N-diisopropylethylamine

1-(6-Bromo-pyridin-2-yl)-3-carboethoxy-thiourea

→

triazolopyridine

5-Bromo-[1,2,4]triazolo[1,5-a]pyridin-2-ylamine

Lösungsmittel

EtOH MeOH

Reaktionsbedingungen

Aufarbeitung

1. 1
   Temperaturthe mixture slowly heated
2. 2
   Temperaturto reflux
3. 3
   Sonstige(Note: bleach scrubber is required to quench H2S evolved)
4. 4
   TemperaturAfter 3 h at reflux
5. 5
   Temperaturto cool
6. 6
   Filtrationfiltered
7. 7
   Sonstigeto collect the precipitated solid
8. 8
   FiltrationFurther product is collected by evaporation in vacuo of the filtrate, addition of H2O (250 mL) and filtration
9. 9
   WaschenThe combined solids are washed successively with H2O (250 mL), EtOH/MeOH (1:1, 250 mL) and Et2O (250 mL)
10. 10
    Sonstigethen dried in vacuo

Vorschrift

To a suspension of hydroxylamine hydrochloride (101.8 g, 1.465 mol) in EtOH/MeOH (1:1, 900 mL) is added N,N-diisopropylethylamine (145.3 mL, 0.879 mol) and the mixture is stirred at room temp. (20° C.) for 1 h. 1-(6-Bromo-pyridin-2-yl)-3-carboethoxy-thiourea (2) (89.0 g, 0.293 mol) is then added and the mixture slowly heated to reflux (Note: bleach scrubber is required to quench H2S evolved). After 3 h at reflux, the mixture is allowed to cool and filtered to collect the precipitated solid. Further product is collected by evaporation in vacuo of the filtrate, addition of H2O (250 mL) and filtration. The combined solids are washed successively with H2O (250 mL), EtOH/MeOH (1:1, 250 mL) and Et2O (250 mL) then dried in vacuo to afford the triazolopyridine derivative (3) as a solid. The compound may be used as such for the next step without any purification. 1H (400 MHz, DMSO-d6) δ 7.43-7.34 (2H, m, 2×aromatic-H), 7.24 (1H, dd, J 6.8 and 1.8 Hz, aromatic-H), 6.30 (2H, br, NH2); m/z 213/215 (1:1, M+H+, 100%).

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