Controlling the Reactivity of Ferrocenyl Carbocations: Routes to Enantiomerically Pure Chlorophosphites and Solid‐State Characterization of a Benzopentalene Dimer

Abstract

A range of enantiopure ferrocenyl diols possessing a variety of electron‐withdrawing groups at the carbinol centre was investigated in the reaction with phosphorus trichloride. Subtle changes in the electronic properties of these groups led, after reaction with phosphorus trichloride, to distinctly different products: α‐substituted ferrocenes, (bis)phosphinic dichlorides, benzopentalene dimers or chlorophosphites. A mechanistic rationale was developed based upon the observed α‐ferrocenyl carbocation behaviour to account for the formation of such diverse products. Two benzopentalene dimers were isolated and successfully characterized by X‐ray crystallography, representing the first examples of such compounds in the solid‐state. The synthesis and characterization of an enantiopure ferrocenophane‐phosphoramidite‐gold(I) complex is also described.

Synthesis of Planar Chiral 2-Aryl Aroylferrocenes via Palladium-Catalyzed C–C Bond-Cleavage/Ring-Opening Reaction

“…We were pleased to find that the yellow color of 2a in 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) quickly changed to deep blue upon the addition of CF 3 CO 2 H (Scheme ). After being quenched with aq NaHCO 3 , the residue was purified by column chromatography on silica gel to deliver 4a in moderate yield, along with a small amount of 2a . The structure was further confirmed by single-crystal X-ray analysis of (±)- 4a (CCDC 2102092).…”