Facile synthesis of 1H-pyrazolo[1,2-a]pyridazine-5,8-dione derivatives by a one-pot, three-component reactions

Synthesis of New Derivatives of Pyridazino[6,1-c]Pyrimido[5,4-e][1,2,4]Triazine; a Novel Heterocyclic System

“…The corresponding rather high field chemical shifts of the pyridazine core have also been previously reported in the literature with similar structures. 30,31 The mass spectrum of 4b showed a molecular ion peak at m/z 319 (M + , containing 35 Cl) consistent with the molecular formula of C 13 H 14 ClN 7 O.…”

The Use of 3,6-Pyridazinediones in Organic Synthesis and Chemical Biology

“…In 2010, Teimouri et al reported the facile synthesis of 1H-pyrazolo[1,2-a]pyridazine-5,8-dione derivatives 21 by a onepot, three-component reaction involving 3 dialkyl acetylenedicarboxylate 19 and an isocyanide 20 (Scheme 3a). 38 The reaction conditions were tolerant of a wide range of isocyanides and dialkyl acetylenedicarboxylates, proceeding in good to excellent yields (70-86%). The mechanism was thought to proceed by reaction of the isocyanide with the acetylenic ester, followed by proton transfer from pyridazinedione.…”

“…[27][28][29][30][31][32][33][34][35] In recent years, 3,6-pyridazinediones have been exploited in several MCRs for the construction of drug-like molecules. [36][37][38][39] The first of these was by Teimouri et al in which the efficient synthesis of biologically relevant pyridazinoindazolones 16 36 was achieved by reaction of 3, 6-pyridazinedione 1, an aldehyde 14 and dimedone 15 in the presence of a catalytic amount of p-toluenesulfonic acid under solvent-free conditions (Scheme 2a). The reaction conditions were tolerant of aliphatic, aromatic and α,β-unsaturated aldehydes, thus demonstrating the broad scope of the reaction with respect to aldehyde.…”

One-pot, three component reactions between isocyanides and dialkyl acetylenedicarboxylates in the presence of phenyl isocyanate: synthesis of dialkyl 2-(alkyl/arylimino)-2,5-dihydro-5-oxo-1-phenyl-1H-pyrrole-3,4-dicarboxylate

“…[8][9][10] The reaction of isocyanides with carbon-carbon triple bonds occurs in a stepwise manner through a zwitterionic intermediate, the ultimate fate of which appears to be dictated by the nature of original triple-bonded substrate. [11][12][13][14][15][16][17][18][19] In continuation of our interest in the application of isocyanides in heterocyclic synthesis, [20][21][22][23][24][25][26][27] we now report the reaction between alkyl/aryl isocyanides 1 and dialkyl acetylenedicarboxylate 2 in the presence of phenyl isocyanate. This one-pot, three component synthesis proceeded spontaneously at 38 ºC in CH 2 Cl 2 and leads to dialkyl 2-(alkyl/arylimino)-2,5-dihydro-5-oxo-1-phenyl-1H-pyrrole derivatives 3a-h (Scheme 1).…”