Making Aromatic Phosphorus Heterocycles More Basic and Nucleophilic: Synthesis, Characterization and Reactivity of the First Phosphinine Selenide.

The synthesis and isolation of a phosphinine selenide was achieved for the first time by reacting red selenium with 2,6-bis(trimethylsilyl)phosphinine. The rather large coupling constant of J =883 Hz is in line with a P-Se bond of high s-character. The σ-electron donating Me Si-substituents significantly increase the energy of the phosphorus lone pair and hence its basicity, making the heterocycle considerably more basic and nucleophilic than the unsubstituted phosphinine C H P, as confirmed by the calculated gas phase basicities.

2-(Dimethylamino)phosphinine: A Phosphorus-Containing Aniline Derivative.

The yet unknown 2-amino-substituted λ ,σ -phosphinines are phosphorus-containing aniline derivatives. Calculations show that the strong interaction of the π-donating NR  group with the aromatic system results in a high π-density at the phosphorus atom. We could now synthesize 2-N(CH ) -functionalized phosphinines, starting from a 3-N(CH ) -substituted 2-pyrone and (CH ) Si-C≡P.