A novel series of optionally substituted 3-(1H-tetrazol-5-yl)-4H-pyrido[1,2-a]pyrimidin-4-ones is provided for use as inhibitors of allergic reactions. The compounds exhibit antiallergy activity by both oral and parenteral routes of administration.
Intramolecular thermal cyclization and benzannulation reactions of the Gould–Jacobs and Conrad–Limpach types were performed in a designed continuousflow reactor system at temperatures in the range of 300–360 °C and under high pressure conditions (100–160 bar) with very short residence times (0.45–4.5 min) in tetrahydrofuran as a low-boiling point solvent. Substituted heteroaromatic compounds including