Synthesis and antiprotozoal activity of [1,3]oxazino[4,5,6-de]quinolines

The synthesis of 1,3-oxazino-anellated 4-amino-5-hydroxy-quinolines has been investigated. Cyclisation to 2,3-dihydro[1,3]oxazino[4,5,6-de]quinoline-2-ones/-2-thiones (2/3) was achieved by reaction with 1,1'-carbonyldiimidazole or 1,1'-thiocarbonyldiimidazole. Cyclocondensation with aldehydes yielded 2,3-dihydro[1,3]oxazino[4,5,6-de]quinoline-derivatives (5). All new tricyclic compounds exhibited weak antiprotozoal activity against Plasmodium falciparum.