Reaktion #92917

Reaktionsgleichung

2-amino-4-methyl-thiazole-5-carboxylic acid, ethyl ester

ethyl 2-ethyl-acetoacetate

→

6-ethyl-3,7-dimethyl-5-oxo-5H-thiazolo[3,2-a]pyrimidine-2-carboxylic acid, ethyl ester

Lösungsmittel

Reaktionsbedingungen

Aufarbeitung

1. 1
   TemperaturAfter cooling
2. 2
   Filtrationdilution with ice water and neutralization with 35% NaOH, the precipitate was filtered
3. 3
   Waschenwashed with water until neutral and
4. 4
   Sonstigecrystallized from hexane

Vorschrift

2-amino-4-methyl-thiazole-5-carboxylic acid, ethyl ester (10 g) was reacted with ethyl 2-ethyl-acetoacetate (17 g) in polyphosphoric acid (50 g) under stirring at 100° C. for 4 hours. After cooling, dilution with ice water and neutralization with 35% NaOH, the precipitate was filtered, washed with water until neutral and crystallized from hexane to give 6-ethyl-3,7-dimethyl-5-oxo-5H-thiazolo[3,2-a]pyrimidine-2-carboxylic acid, ethyl ester, m.p. 122°-124° C. (9.9 g) which was reacted with N-bromo succinimide (13.75 g) in benzene (260 ml) at the reflux temperature for 11 hours.

Quelle