A facile and convenient synthesis of 9-methyl-3(1H-tetrazol-5-YL)-4H-pyrido[1,2-a]pyrimidin-4-one potassium

Article abstract of DOI:10.3987/COM-97-8086

Two convenient synthetic methods of anti-allergy agent, 9-methyl-3-(1H-tetrazol-5-yl)-4H-pyrido[1,2-a]pyrimidin-4-one potassium (1a), are described. Heating of a mixture of malononitrile (2b), 2-amino-3-picoline (4), ethyl orthoformate, and sodium azide in acetic acid, followed by hydrolysis with hydrochloric acid gave 9-methyl-3-(1H-tetrazol-5-yl)-4H-pyrido[1,2-a]pyrimidin-4-one (1b) which was led to 1a by treatment with potassium hydroxide. The use of ethyl cyanoacetate (2a) instead of 2b afforded ethyl 3-(3-methyl-2-pyridylamino)-2-(1H-tetrazol-5-yl)acrylate (8) which was also led to 1a by treatment with potassium hydroxide. 1. The generic name is pemirolast potassium.