New synthesis of fluorinated pyrazoles.
A new synthesis of fluorinated pyrazoles, a class of compounds with potential in medicinal chemistry, is described. The treatment of benzoylfluoroacetonitrile with hydrazine yielded the expected new 3-amino-4-fluoropyrazole, while the analogous reaction of α-cyano-α,α-difluoroketones with hydrazine in refluxing isopropanol surprisingly gave rise to 3-unsubstituted 4-fluoropyrazoles via an unprecedented mechanism. The isolation of intermediate hydrazine adducts led to a mechanistic rationale for this transformation.
Surmont
Riccardo
R
Department of Sustainable Organic Chemistry and Technology, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, B-9000 Gent, Belgium.
Verniest
Guido
G
De Kimpe
Norbert
N
D054879:Halogenation; D006834:Hydrazines / Q000737:chemistry; D015394:Molecular Structure; D011720:Pyrazoles / Q000138:chemical synthesis*
D006834:Hydrazines; D011720:Pyrazoles; C029424:hydrazine