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Microwave assisted regiospecific synthesis of 5‐trifluoromethyl‐4,5‐dihydropyrazoles and—pyrazoles
Author(s) -
Martins Marcos A. P.,
Pereira Claudio M. P.,
Moura Sidnei,
Frizzo Clarissa P.,
Beck Paulo,
Zanatta Nilo,
Bonacorso Helio G.,
Flores Alex F. C.
Publication year - 2007
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.5570440537
Subject(s) - chemistry , phenylhydrazine , trifluoromethyl , toluene , pyrazole , microwave , medicinal chemistry , montmorillonite , solvent , organic chemistry , alkyl , physics , quantum mechanics
The regiospecific synthesis of a series of twelve 5‐trifluoromethyl‐4,5‐dihydropyrazoles and ‐pyrazoles from the cyclocondesation reaction of 4‐alkoxy‐1,1,1‐trifluoro‐3‐alken‐2‐ones [F 3 CC(O)CH=C(R 1 )OR, where R 1 = Me, Et, Pr, iso ‐Pr, Bu, iso‐Bu, Ph, H; and R = Me, Et] with phenylhydrazine in toluene by environmentally benign microwave induced techniques is reported. It is shown that under appropriated conditions, the variation of microwave irradiation power leads to 4,5‐dihydropyrazole or pyrazole derivatives. This paper also includes the use of montmorillonite K‐10 as a solid support for the synthesis of pyrazoles under solvent free conditions.