Katrien Monsieurs

Synthesis of new pyridazino[4,5-c]isoquinolinones by Suzuki cross-coupling reaction

Suzuki cross-coupling reaction of 2-alkyl(methyl and benzyl)-5-chloro-4-methoxy- and 2-alkyl(methyl and benzyl)-4-chloro-5-methoxypyridazin-3(2H)-ones with 2-formylphenylboronic acid afforded the corresponding biaryl products which were cyclized with ammonia to yield hitherto undescribed pyridazino[4,5-c]isoquinolinones. Removal of the N-benzyl protective group in position 2 yielded the unsubstituted tricyclic pyridazinones.

Synthesis of 4-aryl-5-hydroxy- and 5-aryl-4-hydroxypyridazin-3(2H)-ones and their use in the preparation of 4,5-diarylpyridazin-3(2H)-ones and hitherto unknown isochromeno[3,4-d]pyridazinediones

Abstract Easily accessible 2-substituted 4-aryl-5-methoxy- and 2-substituted 5-aryl-4-methoxypyridazin-3(2 H )-ones were transformed into the corresponding aryl-hydroxypyridazin-3(2 H )-ones by alkaline hydrolysis. The use of these compounds in the synthesis of 2-substituted 4,5-diarylpyridazin-3(2 H )-ones with two differently substituted aryl groups was investigated. Two aryl-hydroxypyridazin-3(2 H )-ones, 2-(2-benzyl-5-hydroxy-3-oxo-2,3-dihydropyridazin-4-yl)benzaldehyde and 2-(1-benzyl-5-hydroxy-6-oxo-1,6-dihydropyridazin-4-yl)benzaldehyde, were transformed into 2-benzyl-1 H -isochromeno[3,4- d ]pyridazine-1,6(2 H )-dione and 3-benzyl-3 H -isochromeno[3,4- d ]pyridazine-4,6-dione, respectively, via oxidation of the formyl group with KMnO 4 followed by lactonization.

Synthesis of the dibenzo[f,h]phthalazine and dibenzo[f,h]cinnoline skeleton via a 'Suzuki-Pd-catalyzed intramolecular arylation' and a 'Suzuki-Pschorr' approach

Abstract Palladium-catalyzed intramolecular arylation of 2-benzyl-5-(2-bromophenyl)-4-phenylpyridazin-3(2 H )-one yielded hitherto unknown 2-benzyldibenzo[f,h]phthalazin-1(2 H )-one. The synthesis of this new tetracyclic pyridazinone from 2-benzyl-5-(2-aminophenyl)-4-phenylpyridazin-3(2 H )-one via a Pschorr type reaction was also investigated. Similarly, the construction of 2-methyldibenzo[f,h]cinnolin-3(2 H )-one from 2-methyl-5-(2-bromophenyl)-6-phenylpyridazin-3(2 H )-one and 2-methyl-5-(2-aminophenyl)-6-phenylpyridazin-3(2 H )-one is also reported. Removal of the N -benzyl protective group of 2-benzyl-dibenzo[f,h]phthalazin-1(2 H )-one with AlCl 3 yielded unsubstituted dibenzo[f,h]phthalazin-1(2 H )-one.