%0 Journal Article
%T Green One Pot Solvent-Free Synthesis of Pyrano[2,3-c]-Pyrazoles and Pyrazolo[1,5-a]Pyrimidines
%A Hamad M. Al-Matar
%A Khaled D. Khalil
%A Aisha Y. Adam
%A Mohamed H. Elnagdi
%J Molecules
%D 2010
%I MDPI AG
%R 10.3390/molecules15096619
%X Pyrano[2,3-c]pyrazoles are obtained via mixing ethyl acetoacetate, hydrazine hydrate, aldehydes or ketones and malononitrile in the absence of solvent. These same products were also obtained by reacting arylidenemalononitriles 3 with 3-methyl-2-pyrazolin-5-ones. NOE difference experiments confirmed that these products exist solely in the 2H form. Similar treatments of 3-amino-2-pyrazolin-5-one with arylidene-malononitrile afforded adduct 6. Similarly mixing ethyl cyanoacetate, hydrazine hydrate, aldehydes, with malononitrile gave the same product 6. A novel synthesis of 4-oxo-4H-pyrano[2,3-c]pyrazole (8) could be achieved via reacting 3-methyl-2-pyrazolin-5-one with a mixture of cyanoacetic acid and acetic anhydride. Similar treatment of 3-aminopyrazole 11 with the benzylidene-malononitrile produced the pyrazolo[2,3-a]pyrimidines 12a,b.
%K pyranopyrazole
%K multi-component synthesis
%K aminopyrazolinone
%K pyrazolo[1
%K 5-a]pyrimidine
%K cyanoacetic acetic anhydride
%K NOE difference experiments
%U http://www.mdpi.com/1420-3049/15/9/6619