Synthesis of New 4-Benzoyl-5-hydroxy-3-Trifluoromethylpyrazole Derivatives via [1,3] Rearrangements of Benzoyl Group Using tert - Butyllithium

Abstract

The 4-benzoyl-3-trifluoromethyl-5-p-toluenesulfonyloxypyrazole derivatives (7a − c) were synthesized by a new procedure involving rearrangement of the benzoyl groups in 5-benzoyloxy-4-bromo-3-trifluoromethylpyrazole derivatives (5a − c) to 4-benzoyl-5-hydroxy-3-trifluoromethylpyrazoles (6a − c) via lithium-bromide exchange using tert-butyllithium.

Notes

JP-A-63–122672, JP-A-63–122673, JP-A-63–170365, JP-A-2–173, JP-A-2–288866

Although the wavenumbers of carbonyl absorption in compounds 6 and 7 are lower than usual carbonyl groups in the IR spectra, these values are in good agreement with those reported for the other 4-benzoylpyrazoles, see reference 1(a)