Organophosphorus Compounds; 104. Functionalization of a Pentacyclic Phosphorus-Carbon Cage Compound at Phosphorus

Depending on the reaction partners employed, the two phosphane functions in the pentacyclic cage compound 5 exhibit different reactivities. On reaction with alkyl halides (→ 8a-d) and o-benzoquinones (→ 17a-c), the expected increase in coordination at the all-carbon-substituted, more nucleophilic λ ³ σ ³-phosphorus atom P12 in the pentacyclic system 5 is observed to occur preferentially. Functionalizations with organic azides (Staudinger reaction, → 10a-c), tert-butyl hydroperoxide, cyclooctasulfur, and gray selenium (→ 13a-c), on the other hand, occur at the oxygen-substituted, more electrophilic λ ³ σ ³-phosphorus atom P2. In addition to electronic factors, steric interactions are implicated in the interpretation of the regiochemistry. The structure elucidations of the prepared derivatives of the cooligomeric cage compound 5 were based on NMR spectroscopic methods including selective irradiation and two-dimensional techniques. An X-ray crystal structure analysis of the phosphonium salt 8a has also been carried out.

phosphorus-carbon cage compounds - functionalization - quaternization - Staudinger reaction - oxidation