One-step methylation of aromatic phosphorus heterocycles: synthesis and crystallographic characterization of a 1-methyl-phosphininium salt

For the first time, the direct synthesis of 1-methyl-phosphininium salts has been achieved by reacting aromatic lambda(3),sigma(2)-phosphinines with the readily available dimethyl chloronium salt [(CH3)(2)Cl](+)[Al(OTeF5)(4)](-). The remarkably high electrophilicity of the alkylation reagent in combination with the weakly coordinating pentafluoro-orthotelluratoaluminate anion offers excellent conditions for this one-step approach. Our simple and quantitative access to 1-methyl-phosphininium salts will pave the way to explore the chemistry of such reactive species in more detail.

Automated summary

The direct synthesis of 1-methyl-phosphininium salts was achieved for the first time by reacting aromatic lambda(3),sigma(2)-phosphinines with dimethyl chloronium salt [(CH3)(2)Cl](+)[Al(OTeF5)(4)](-). The high electrophilicity of the alkylation reagent in combination with the weakly coordinating pentafluoro-orthotelluratoaluminate anion provides excellent conditions for this one-step approach. This simple and quantitative access to 1-methyl-phosphininium salts will pave the way for further exploration of the chemistry of such reactive species.