Synthesis and elaboration of all-cis-1,2,4,5-tetrafluoro-3-phenylcyclohexane: a polar cyclohexane motif

Abstract

A stereocontrolled synthesis of all-cis-1,2,4,5- tetrafluoro-3-phenylcyclohexane is developed as the first functionalised example of this polar cyclohexane motif. The dipolar nature of the ring, arising due to two 1,3-diaxial C-F bonds, is revealed in the solid-state (X-ray) structure. The orthogonal conformation of the aryl and cyclohexyl rings in all-cis-1,2,4,5-tetrafluoro-3-phenylcyclohexane, and in an ortho-nitro derivative, result in intramolecular (1h)JHF and (2h)JCF NMR couplings relayed through hydrogen bonding. The aryl group of all-cis-1,2,4,5-tetrafluoro-3-phenylcyclohexane is elaborated in different ways to demonstrate the versatility of this compound for delivering the motif to a range of molecular building blocks.

Keywords: aromatic transformations; cyclohexane; fluorinations; organofluorine compounds; polar organic motifs.