Titel
Synthesis of tetrasubstituted pyrazoles containing pyridinyl substituents
Autor*in
Ashenafi Damtew Mamuye
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Abstract
A synthesis of tetrasubstituted pyrazoles containing two, three or four pyridinyl substituents is described. Hence, the reaction of 1,3-dipyridinyl-1,3-propanediones with 2-hydrazinopyridine or phenylhydrazine, respectively, affords the corresponding 1,3,5-trisubstituted pyrazoles. Iodination at the 4-position of the pyrazole nucleus by treatment with I2/HIO3 gives the appropriate 4-iodopyrazoles which served as starting materials for different cross-coupling reactions. Finally, Negishi cross-coupling employing organozinc halides and Pd catalysts turned out to be the method of choice to obtain the desired tetrasubstituted pyrazoles. The formation of different unexpected reaction products is described. Detailed NMR spectroscopic investigations (1H, 13C, 15N) were undertaken with all products prepared. Moreover, the structure of a condensation product was confirmed by crystal structure analysis.
Stichwort
Negishi couplingNMR (1H13C15N)pyrazolepyridineX-ray structure analysis
Objekt-Typ
Sprache
Englisch [eng]
Persistent identifier
Erschienen in
Titel
Beilstein Journal of Organic Chemistry
Band
13
Seitenanfang
895
Seitenende
902
Publication
Beilstein Institut
Erscheinungsdatum
2017
Zugänglichkeit
Rechte
Rechteangabe
© 2017 Jansa et al.
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