A Green and Convenient Route for the Regioselective Synthesis of New Substituted 3-Aryl-5H-indeno[1,2-c]pyridazines as Potential Monoamine Oxidase Type A Inhibitors

Several indeno[1,2-c]pyridazines were efficiently synthesised using the one-pot, three-component reaction of substituted indanones, arylglyoxalmonohydrates, and hydrazine in the presence of 1,5-diazabicyclo[4,3,0]non-5-ene (DBN) in water at room temperature. These substituted 3-aryl indeno[1,2-c]pyridazines can be considered as potential monoamine oxidase type A (MAOA) inhibitors. The advantages of this new strategy are the novelty of the indenopyridazine derivatives, high regioselectivity, use of water as the solvent, no requirement for toxic metal catalysts, and good to excellent yields.

Synthesis of [1,2,4]Triazolo[4″,3″:1′,6′]Pyrimido[4′,5′:3,4]Pyridazino[1,6-D] [1,2,4]Triazine; A Novel Tetracyclic System

The condensation reaction of 6-acetyl-3-amino-5-aryl-2-phenyl-2,5-dihydropyridazine-4-carbonitrile with triethyl orthoformate and then with hydrazine hydrate to obtain the new fused bicyclic 4-aryl-5-hydrazinyl-3-(1-hydrazonoethyl)-1-phenyl-1,4-dihydropyrimido[4,5-c]pyridazines via the Dimroth rearrangement is reported. Further cyclisation was achieved by the treatment of latter compounds with triethyl orthoformate to afford several derivatives of a novel tetracyclic fused system [1,2,4] triazolo[4″,3″:1′,6′]pyrimido[4′,5′:3,4]pyridazino[1,6-d][1,2,4]triazine.

An Efficient One-pot Two-component Protocol for Regio- and Chemoselective Synthesis of 5-Aryloyl-1,3,7,9-tetraalkyl-2,8-dithioxo-2,3,8,9-tetrahydro-1H-pyrano[2,3-d:6,5-d′]dipyrimidine-4,6(5H,7H)-diones

Novel symmetric fused pyrano[2,3-d]pyrimidine derivatives were synthesized in 75–92 % yield by a one-pot two-component reaction of arylglyoxals and 1,3-dialkyl-2-thiobarbituric acids in ethanol at room temperature. This is the first protocol to be reported for the synthesis of 5-aryloyl-1,3,7,9-tetraalkyl-2,8-dithioxo-2,3,8,9-tetrahydro-1H-pyrano[2,3-d:6,5-d′]dipyrimidine-4,6(5H,7H)-diones and the significant features of the present protocol are simplicity, high yields, a simple isolation procedure, and high chemoselectivity.

A Regioselective One-Pot, Three Component Synthesis of 6-Aryl-4-cyano-3(2H)-pyridazinones in Water

A series of 4-cyano-3(2H)-pyridazinones bearing different aryl substituents in the 6-position of the pyridazinone ring was synthesized regioselectively using a novel efficient one-pot three component reaction of alkyl 2-cyanoacetates with arylglyoxals in the presence of hydrazine hydrate at room temperature in water.