An unexpected formation of pyrazolopyrimidines during the attempted to obtain 5-substituted tetrazoles from carbonitriles

In this Letter, we described the synthesis of new 5-(5-amino-1-aryl-1H-pyrazole-4-yl)-1H-tetrazoles 2a–c from 5-amino-1-aryl-1H-pyrazole-4-carbonitriles 1a–c as well as the unexpected 1H-pyrazolo[3,4-d]pyrimidine derivatives 6a–c from 5-amino-1-aryl-3-methyl-1H-pyrazole-4-carbonitriles 4a–c, instead...

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Bibliographic Details
Published in:Tetrahedron letters 2013-10, Vol.54 (42), p.5748-5750
Main Authors: Faria, Jéssica Venância, dos Santos, Maurício Silva, Vegi, Percilene Fazolin, Borges, Julio Cesar, Bernardino, Alice M.R.
Format: Article
Language:English
Subjects:
Analogue
Cycloaddition
Derivatives
Pyrazole
Pyrazolo[3,4-d]pyrimidine
Pyrazolopyrimidines
Rings (mathematics)
Synthesis
Tetrahedrons
Tetrazole
Tetrazoles
Unexpected reaction
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Summary:In this Letter, we described the synthesis of new 5-(5-amino-1-aryl-1H-pyrazole-4-yl)-1H-tetrazoles 2a–c from 5-amino-1-aryl-1H-pyrazole-4-carbonitriles 1a–c as well as the unexpected 1H-pyrazolo[3,4-d]pyrimidine derivatives 6a–c from 5-amino-1-aryl-3-methyl-1H-pyrazole-4-carbonitriles 4a–c, instead of 5-(5-amino-1-aryl-3-methyl-1H-pyrazole-4-yl)-1H-tetrazoles 5a–c as desired. In an attempt to obtain these tetrazole derivatives containing the methyl group at C3-position in the pyrazole ring, the amino group in 5-amino-1-(4-methoxyphenyl)-3-methyl-1H-pyrazole-4-carbonitrile 4c was protected by the reaction with sodium hydride and di-tert-butyl-dicarbonate (Boc). The tetrazole derivative 5c was synthesized from the protected compound 7c using analogue methodology to obtain 2a–c and 6a–c.
ISSN:0040-4039
1873-3581
DOI:10.1016/j.tetlet.2013.08.033