A 2.00N benzylmagnesium chloride solution (1.35 ml; 2.70 mmol) in THF is added dropwise to a solution of the bromide 6 (340 mg; 0.67 mmol) in THF (10 ml), which is stirred at -78° C. under an argon atmosphere. After stirring at -70° C. for 3 hours, the reaction solution is warmed to room temperature and mixed with saturated aqueous ammonium chloride solution (50 ml). The aqueous phase is extracted with ethyl acetate (3×60 ml). The combined organic phase is dried over Na2SO4 and concentrated under reduced pressure. After purification by column chromatography on silica gel (ethyl acetate/heptane), the bisalkylated phosphinic acid ester 10 (105 mg, 30% of theory) is obtained.
