Condensation reactions of 3-oxo-2-arylhydrazonopropanals with active methylene reagents: formation of 2-hydroxy- and 2-amino-6-substituted-5-arylazonicotinates and pyrido[3,2-c]cinnolines via 6π-electrocyclization reactions.
3-Oxo-3-phenyl-2-(p-tolylhydrazono)propanal (1a) undergoes condensation with ethyl cyanoacetate in acetic acid in the presence of ammonium acetate to yield either 2-hydroxy-6-phenyl-5-p-tolylazonicotinic acid ethyl ester (6a) or 2-amino-6-phenyl-5-ptolyl-azonicotinic acid ethyl ester (8), depending on the reaction conditions. Similarly, other 3-oxo-3-aryl-2-arylhydrazonopropanals 1a,b condense with active methylene nitriles 2c,d to yield arylazonicotinates 6b,c. In contrast, 2-[(4-nitrophenyl)-hydrazono]-3-oxo-3-phenyl-propanal (1c) reacts with ethyl cyanoacetate to yield ethyl 6-(4-nitrophenyl)-2-oxo-2,6-dihydropyrido[3,2–c]cinnoline-3-carboxylate (11), via a novel 6π-electrocyclization pathway. Finally, 3-oxo-2-(phenylhydrazono)-3-p-tolylpropanal (1d) condenses with 2a-c to yield pyridazinones 13a-c.
Chemistry Department, Faculty of Science, Kuwait University, P.O. Box 5969, Safat 13060, Kuwait. saleh.almousawi@yahoo.com
Saleh M
SM
Al-Mousawi
Morsy A
MA
El-Apasery
D000447:Aldehydes / Q000737:chemistry; D002236:Carbohydrate Conformation; D006574:Heterocyclic Compounds, 2-Ring / Q000737:chemistry; D006835:Hydrazones / Q000737:chemistry*; D008958:Models, Molecular; D009539:Nicotinic Acids / Q000138:chemical synthesis* / Q000737:chemistry; D011724:Pyridazines / Q000737:chemistry
D000447:Aldehydes; D006574:Heterocyclic Compounds, 2-Ring; D006835:Hydrazones; D009539:Nicotinic Acids; D011724:Pyridazines; C005556:propionaldehyde; C476282:cinnoline