3,5-Di-tert-butylbromobenzene (12.50 g, 46.43 mmol) was added dropwise to magnesium (1.70 g, 69.96 mmol) and THF (50 mL) in an argon atmosphere. After the dropwise addition, the mixture was heated under reflux for 1 hour. The reaction mixture was cooled to ambient temperature and filtered, and the thus-obtained THF solution of 3,5-di-tert-butylphenylmagnesium bromide, and 1,2-bis(dichlorophosphino)benzene (2.00 g, 7.15 mmol) were reacted as in Production Example 1. The reaction was allowed to proceed overnight at 60° C. After purification, the title compound was obtained as a white powder (4.66 g, yield 73%).
