Preparation of the bisphosphinite ligand

Chlorophosphines need to be manipulated carefully with gloves and eye protection. They can cause burns, irritation to eyes and irritation to the respiratory system. 

Different chlorophosphines can be synthesised, or are available from Strem or Digital Chemicals. 

Two lOOmL Schlenk flasks, each equipped with a magnetic stirrer bar, were dried at 150 °C overnight, cooled under vacuum and then flushed with nitrogen. 

One of the Schlenk tubes was filled with (—)-(lR, 3R, 5R, 6S)-bicyclo [3.2.0] heptan-3,6-diol (500 mg) dissolved in dry tetrahydrofuran (20 mL) under nitrogen, then triethylamine (0.87 g) was added. 

The solution was cooled to 0°C in an ice-bath, and then the chloropho-sphine (2.2 g) was added dropwise via a syringe over 5 minutes with stirring. A white precipitate of triethylammonium chloride appeared. When the addition was complete, the ice-bath was removed and the stirring was continued at ambient temperature for 15 hours. 

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