Reaction of 3-amino-acridine with formaldehyde in acidic medium: Influence of the stoechiometry on the reaction products

3-amino-acridine 1 reacts with formaldehyde in acidic medium to give four different compounds depending on the stoechiometry of the reaction: the dihydrooxazine derivative 2, the tetrahydropyrimidine derivative 3, the Troger's Base analogue 4 and the acridino[3,4-j]-benzo[b][1,7]phenanthroline 5. Compounds 3, 4 and 5 could be obtained selectively by using the required amount of formaldehyde. Selective synthesis of 2 was independently realized in a three step sequence. Compounds 2, 3 and 4 in solution in 12 N HCl slowly transformed to give compound 5 as a major product. (C) 1997 Elsevier Science Ltd.