Nitrogen bridgehead compounds. Part 65. Vilsmeier-haack formylation of 4H-pyrido[1,2-a]pyrimidin-4-ones. Part 6

2-Substituted 3-formyl-4H-pyrido1,2-a]pyrimidin-4-ones can be synthethized by Vilsmeier-Haack formylation with the dimethylformamide-phosphoryl chloride complex only from those 4H-pyrido1,2-a]pyrimidin-4-ones which contain a substituent with electron-releasing resonance effect in position 2. The products were characterized by uv, ir and ¹H nmr spectroscopy.