Formamidine acetate → 6-chloro-1H-pyrido[2,3-d]pyrimidin-4-one

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Reaction Steps

A mixture of 2-amino-5-chloro-nicotinic acid ethyl ester (1.5 g, 7.38 mMol) and formamidine acetate (3.1 g, 29.51 mMol) in 2-ethoxyethanol (50 mL) was heated at reflux overnight. The solution was cooled to room temperature, and allowed to stand for 2 hours. The resulting precipitate was collected by filtration, rinsed with a small amount of 2-ethoxyethanol followed by diethyl ether (10 mL), and allowed to air dry. The filtrate was concentrated in-vacuo, and the residue was triturated with methylene chloride. The resulting solids were combined with the solids from the earlier filtration, and this material was crystallized from methanol to yield 475 mg of tan needles as product, in three crops. MS (ES+)=182 (M+H)+. Yield=37%.

Provenance & Evidence