A FACILE AND CONVENIENT SYNTHESIS OF (1H-TETRAZOL-5-YL)-4H-PYRIDO[1,2-A]PYRIMIDIN-4-ONE POTASSIUM

Two convenient synthetic methods of anti-allergy agent, (1H-tetrazol-5 -yl)-4H-pyrido[1,2-a]pyrimidin-4-one potassium (1a), are described. He ating of a mixture of malononitrile (2b), 2-amino-3-picoline (4), ethy l orthoformate, and sodium azide in acetic acid, followed by hydrolysi s with hydrochloric acid gave (1H-tetrazol-5-yl)-4H-pyrido[1,2-a]pyrim idin-4-one (1b) which was led to 1a by treatment with potassium hydrox ide. The use of ethyl cyanoacetate (2a) instead of 2b afforded ethyl e thyl-2-pyridylamino)-2-(1H-tetrazol-5-yl)acrylate (8) which was also l ed to 1a by treatment with potassium hydroxide.