A Tautomeric λ³/λ⁵-Phosphane Pair and Its Ambiphilic Reactivity

Abstract

The central phosphorus atom of a novel hydroxyl-functionalized triarylphosphane was shown to reversibly insert into one of the molecule’s O–H bonds, which forms the basis for a tautomeric λ3/λ5-phosphane equilibrium. For the first time, this equilibrium was detected for a λ3-triarylphosphane and the underlying dynamic process was elucidated by NMR spectroscopy. On the basis of reactivity studies, a nucleophilic character was assigned to the minor species present in solution, the λ3-phosphane. Upon methylation, for example, the λ3-form was selectively removed from the equilibrium and converted to the corresponding phosphonium salt. However, upon generation of an alkoxide via proton abstraction, the electrophilic character of the λ5-phosphane in the equilibrium became evident since the alkoxide was found to attack the molecule’s phosphorus atom. This intramolecular reaction led to the selective formation of a new anionic λ6-hydridospirophosphane.

Martin’s Phosphino-Triol Revisited: Unexpected P–C Bond Cleavage Reactions and Their Suppression via Complexation of Al3+ and Sc3+

“…compound 4-Me , see Scheme ), presumably due to the rather harsh workup conditions (H 2 SO 4 /thf, reflux, 12 h) . Hence, we decided to redesign and optimize Martin’s synthesis starting from 5-Me (R = Me) and 5-H ( R = H), respectively (see Scheme ). To start with, compounds 5 (R = H, Me) were reacted with PhLi to generate the corresponding ortho -lithiated alkoxides via I/Li-exchange, which were quenched in situ via addition of PCl 3 (0.33 equiv).…”

Synthesis, Structure and Reactivities of Pentacoordinated Phosphorus–Boron Bonded Compounds

“…The lack of a coordination solvent allows the rearrangement to occur spontaneously upon hydride abstraction accompanied by the reduction of methyl triflate. It should be mentioned that the coordinatively stabilised phosphine is readily accessible starting from the corresponding phosphorane …”

Synthesis, Structure and Reactivities of Pentacoordinated Phosphorus–Boron Bonded Compounds

“…[33] Additionally, it was discovered that from the corresponding phosphorane. [56] Scheme 2. Reactions of phosphoranyl-borate 1a.…”