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Microwaves in organic synthesis: Synthesis of pyridazinones, phthalazinones and pyridopyridazinones from 2‐oxo‐arylhydrazones under microwave irradiation
Author(s) -
AlSaleh Balkis,
ElApasery Morsy Ahmed,
Hilmy Noha M.,
Elnagdi Mohamed H.
Publication year - 2006
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570430622
Subject(s) - chemistry , yield (engineering) , dimethylformamide , piperidine , microwave irradiation , acetic acid , ammonium acetate , microwave , organic chemistry , nuclear chemistry , medicinal chemistry , catalysis , solvent , materials science , high performance liquid chromatography , physics , quantum mechanics , metallurgy
The phenylhydrazones 1a‐d condensed with ethyl cyanoacetate to yield pyridazinones 2a‐d that reacted with sulphur in presence of piperidine to yield the aminothienopyridazineones 3a,b that reacted with electron poor olefins and acetylenes to yield phthalazines 10‐12. The condensed aminothiophenes 3a,b reacted with dimethylformamide dimethylacetal to yield amidines 13a,b. Compounds 2a,b condensed with dimethylformamide dimethylacetal to yield the trans enamines 16a,b that cyclized readily into the pyridopyridazinones 17a,b on treatment with ammonium acetate in presence of acetic acid. Compounds 2a‐d reacted also with benzylidenemalononitrile to yield the phthalazinones 21a‐d. The reactions were conducted both by microwave heating and conventional heating. Better yields in much shorter reaction times were achieved by microwave heating.