1.1-Dimethyl-1-methoxy-1λ5phospholan und -phosphorinan: Synthese, Struktur und dynamisches Verhalten / 1,1 -Dimethyl-1-methoxy-1λ5 phospholane and -phosphorinane: Synthesis, Structure and Dynamic Behaviour

Abstract

The title compounds have been prepared in high yields from equimolar amounts of methanol and the ylides 1-methyl-1-methylene-phospholane and -phosphorinane, respectively. On the basis of a variable temperature 1H, 13C, and 31P NMR study the compounds have been assigned a molecular structure with a pentacovalent phosphorus atom in a trigonal bipyramidal configuration and the methoxy group in an axial position. The molecules are fluxional on the NMR time scale and rapid ligand scrambling is observed at room temperature, predominantly affecting the ring systems. At elevated temperatures an irregular, intermolecular exchange of methoxy groups and CH3P-protons is observed, which is a consequence of a retro cleavage to form ylide and methanol. This process is faster with the phosphorinane than with the phospholane.