α,β-Disubstituted CF3-Enones as a Trifluoromethyl Building Block: Regioselective Preparation of Totally Substituted 3-CF3-Pyrazoles

J Org Chem. 2021 Feb 5;86(3):2385-2405. doi: 10.1021/acs.joc.0c02516. Epub 2021 Jan 10.

Abstract

An efficient pathway toward a novel class of trifluoromethyl building blocks was elaborated. The reaction of α-CF3-enamines with arylaldehydes resulted in direct synthesis of α,β-diaryl-CF3-enones isolated in up to 93% yield as E-isomers. The possible reaction mechanism was proposed using the Zimmerman-Traxler model. The reaction of α,β-diaryl-CF3-enones with hydrazines opens a novel pathway to trifluoromethylated pyrazolines. Oxidation of pyrazolines with DDQ opened access to totally regioselective preparation of 3-CF3-pyrazoles isolated in high yield. Using this strategy, 4-arylated derivatives of known drugs Celebrex, Mavacoxib, and SC-560 can be synthesized.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Hydrazines*
  • Oxidation-Reduction
  • Pyrazoles*

Substances

  • Hydrazines
  • Pyrazoles