Oxonium, trimethyl-, tetrafluoroborate(1-) (1:1) → (+/-)-5,8-Dihydro-4-methoxy-7-methyl-5-(3-nitrophenyl)pyrido[2,3-d]pyrimidine-6-carboxylic acid isopropyl ester

Participants

Reaction Steps

Three and 0.7 g (10 mmol) (±)-3,4,5,8-tetrahydro-7-methyl-5-(3-nitrophenyl)-4-oxo-pyrido[2,3-d]-pyrimidine-6-carboxylic acid isopropyl ester and 3.0 g (20 mmol) trimethyloxonium-tetrafluoroborate are stirred in 150 ml 1,2-dichloroethane in nitrogen atmosphere and at room temperature for three hours. The product is extracted twice with 50 ml saturated sodium hydrogen carbonate solution, the organic phase is separated, dried over sodium sulfate and reduced under vacuum. Twice recrystallizing the residue from diisopropyl ether/isopropanol yields the product in the form of colorless crystals with a mp of 212°-213° C.

Provenance & Evidence