One‐Pot Synthesis of a 1,2‐Diphospholide by Double C–H Deprotonation

The relationship between phosphorus and carbon chemistry has been realized for many years. Phosphorus relatives of classical organic ligands (like cyclopentadienide, Cp – ) in which carbon atoms have been substituted for phosphorus atoms are important classes of organometallic ligands, which are relevant to catalysis. Often, however, a limit to applying the phosphorus counterparts is the low‐yielding and circuitous nature of their synthesis. A case in point is the 1,2‐diphospholide ligand framework, an important analogue of the cyclopentadienyl ligand, which has only been obtained from multistep syntheses. We report in this paper a high‐yielding and direct route to this type of framework using a very simple approach. Treatment of MesPHLi (Mes = 2,4,6‐trimethylphenyl) with Sb(NMe 2 ) 3 generates the 5,7‐dimethyl‐1,2‐benzodiphosphol‐1‐ide anion ( 1 ), the first 1,2‐diphospholide analogue of indenyl. Structural and NMR spectroscopic investigations suggest that this unique reaction, involving double C–H deprotonation of a CH 3 group of the Mes ligand, occurs through the rearrangement of a tetraphospha‐1,4‐diide anion.