An Iron-Catalyzed Route to Dewar 1,3,5-Triphosphabenzene and Subsequent Reactivity

Adam N Barrett; Martin Diefenbach; Mary F Mahon; Vera Krewald; Ruth L Webster

doi:10.1002/anie.202208663

An Iron-Catalyzed Route to Dewar 1,3,5-Triphosphabenzene and Subsequent Reactivity

Angew Chem Int Ed Engl. 2022 Sep 12;61(37):e202208663. doi: 10.1002/anie.202208663. Epub 2022 Aug 9.

Authors

Adam N Barrett¹, Martin Diefenbach², Mary F Mahon¹, Vera Krewald², Ruth L Webster¹

Affiliations

¹ Department of Chemistry, University of Bath, Claverton Down, Bath, BA2 7AY, UK.
² Department of Chemistry, TU Darmstadt, 64287, Darmstadt, Germany.

Abstract

The application of an alkyne cyclotrimerization regime with an [Fe(salen)]₂ -μ-oxo (1) catalyst to triphenylmethylphosphaalkyne (2) yields gram-scale quantities of 2,4,6-tris(triphenylmethyl)-Dewar-1,3,5-triphosphabenzene (3). Bulky lithium salt LiHMDS facilitates a rearrangement of 3 to the 1,3,5-triphosphabenzene valence isomer (3'), which subsequently undergoes an intriguing phosphorus migration reaction to form the ring-contracted species (3''). Density functional theory calculations provide a plausible mechanism for this rearrangement. Given the stability of 3, a diverse array of unprecedented transformations was investigated. We report novel crystallographically characterized products of successful nucleophilic/electrophilic addition and protonation/oxidation reactions.

Keywords: Electrophilic Addition; Iron; Nucleophilic Addition; Phosphorus Heterocycles; Reaction Mechanisms.

Abstract

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