Acetic Acid → 3-methyl-5,6,7,8-tetrahydro-1H-pyrido[4,3-d]pyrimidine-2,4-dione

Beteiligte Stoffe

Reaktionsschritte

A solution of 96 g of 6-benzyl-3-methyl-5,6,7,8-tetra-hydro-1H-pyrido[4,3-d]pyrimidine-2,4-dione from c) in 1.5 1 of glacial acetic acid was debenzylated by hydrogenolysis for 6 h on 14.6 g of 10% palladium/activated charcoal at 25° C. and 3.5 bar. After the catalyst had been filtered off, the filtrate was concentrated under reduced pressure. The above preparation was repeated. The two crude products were combined, dissolved in water and precipitated, with stirring, by the addition of 33% sodium hydroxide solution to pH 6.9. The precipitate was washed with water and dried at 60° C. under reduced pressure to give 115.3 g of 3-methyl-5,6,7,8-tetrahydro-1H-pyrido[4,3-d]pyrimidine-2,4-dione.

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