1. In a 1L three-necked flask, 32.5 g of 2-bromo-1,3,5-triisopropylbenzene, 5.6 g of magnesium shavings, and 300 mL of anhydrous tetrahydrofuran (THF) were added to prepare a Grignard reagent.
2. Under stirring, 20 g of 2-bromochlorobenzene was slowly added dropwise to the above solution to form 2,4,6-triisopropyl-2'-bromodiphenyl Grignard reagent, and the reaction was refluxed for 2 hours.
3. After completion of the reaction, cooled to room temperature, 2.4 g of tetrakis(triphenylphosphine)palladium was added as a catalyst and stirred for 30 minutes.
4. At room temperature, 18.8 g of di-tert-butylphosphonium chloride was slowly added dropwise to the reaction mixture and the reaction was continued at reflux for 5 hours.
5. The reaction mixture was cooled in an ice water bath and 200 mL of saturated aqueous ammonium chloride solution was slowly added dropwise to quench the reaction.
6. The organic phase was separated and crystallized by addition of methanol and filtered to afford 41.7 g of the white solid product 2-di-tert-butylphosphino-2',4',6'-triisopropylbiphenyl in 94% yield.