Green One Pot Solvent-Free Synthesis of Pyrano[2,3-c]-Pyrazoles and Pyrazolo[1,5-a]Pyrimidines

Molecules

Hamad M. Al-Matar¹  Khaled D. Khalil¹  Aisha Y. Adam¹ 

[1] ¹Chemistry Department, Faculty of Science, University of Kuwait, P.O. Box 5969, Safat, 13060 Kuwait ²Chemistry Department, Faculty of Science, Cairo University, Giza, 12613, Egypt

关键词: pyranopyrazole;    multi-component synthesis;    aminopyrazolinone;    pyrazolo[1;    5-a]pyrimidine;    cyanoacetic acetic anhydride;    NOE difference experiments;   

DOI  :  10.3390/molecules15096619

来源: mdpi

【 摘 要 】

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.

【 授权许可】

CC BY   
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