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Alkylation and arylation of pyrazoles under solvent‐free conditions: Conventional heating versus microwave irradiation
Author(s) -
Almena Inés,
DízBarra Enrique,
De La Hoz Antonio,
Ruiz Juliana,
SínchezMigallón Ana,
Elguero José
Publication year - 1998
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570350604
Subject(s) - chemistry , microwave irradiation , alkylation , microwave , solvent , microwave heating , irradiation , photochemistry , organic chemistry , catalysis , nuclear physics , physics , quantum mechanics
The use of sodium hydrogen carbonate under solvent‐free conditions and microwave irradiation is by far the best method for N‐ alkylating pyrazoles. The yields are good and the method is devoid of side reactions (quaternization, isomerization, hydrogen halide elimination). Solvent‐free conditions are the only ones that allow us to prepare 1‐substituted pyrazoles from secondary halides. The procedure using quaternary salts in one‐pot provides an interesting alternative for the preparation of 1‐heteroarylpyrazoles.