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Synfacts 2007(4): 0365-0365
DOI: 10.1055/s-2007-968375
DOI: 10.1055/s-2007-968375
Synthesis of Heterocycles
© Georg Thieme Verlag Stuttgart · New York
One-Pot Synthesis of Pyrazolo[1,2-b]phthalazinediones
M. B. Teimouri
Iran Polymer and Petrochemical Institute, Tehran, Iran
Weitere Informationen
Publikationsverlauf
Publikationsdatum:
23. März 2007 (online)
![](https://www.thieme-connect.de/media/synfacts/200704/lookinside/thumbnails/10.1055-s-2007-968375-1.jpg)
Significance
A three-component synthesis of pyrazolophthalazinediones from alkyl isocyanides, dialkylacetylene dicarboxylates and phthalhydrazide is reported. The scope of this reaction is not well exploited. Bulky groups on isocyanide and acetylene dicarboxylate (R1 = R2 = t-Bu) lead to low yield (55%) while higher yield (77%) is observed when less-hindered groups (R1 = cyclohexyl, R2 = Me) are involved. The reaction is proposed to proceed via a mixture of cis- and trans-vinylisonitrilium intermediates, which, upon 1,2- or 1,4-addition, isomerization (as necessary), and cyclization, leads to the formation of the observed products.