Efficient One-Pot Synthesis of Secondary Cyclic Phosphanes with Easy Regeneration of the Phosphorus-Donor Reagent Used

Phosphanes: No pain, all gain. A regenerable phosphorus donor is the key to an efficient and economic one‐pot synthesis of five‐ and six‐membered secondary cyclic phosphanes. The reaction, at room temperature, of 1 with 1 equivalent of bis(Grignard reagent) 2 followed by treatment with aqueous acid gives cyclic phosphanes 3 in 70–80 % yield and the new compound 4. Simply treating 4 with PCl3 quantitatively regenerates the starting reagent 1, which can be reused without further purification.