1,1-Diphenylethylene → 2-Bromo-1,1-diphenylethylene

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Reaction Steps

20 g (111 mmoles) of 1,1-diphenylethylene was dissolved in 70 ml of cyclohexane, to which was then added dropwise 35 g (222 mmoles) of bromine at room temperature. The mixture was stirred at the same temperature for 20 hours and further heated under reflux for one hour. After cooling, the reaction mixture was washed with a sodium thiosulfate aqueous solution and saturated salt water, and an organic phase was separated by liquid separation. The organic phase was concentrated and subjected to Kugel distillation (at 145 to 148° C./0.6 Torr) to obtain 24 g (yield: 86%) of desired 1,1-diphenyl-2-bromoethylene. 4.8 g (18 mmoles) of 1,1-diphenyl-2-bromoethylene, 0.486 g (20 mmoles) of Mg, a small piece of iodine, and 100 mL of THF were added to a 300 ml eggplant type flask to prepare a Grignard reagent. The reaction mixture was cooled to −78° C., to which trimethoxyborane was then added dropwise while maintaining the same temperature. The mixture was stirred at room temperature for 2 hours, to which 2N hydrochloric acid was then added. An organic phase was treated to isolate desired 1,1-diphenylvinylboronic acid as a white powder in a yield of 35%. The same procedures as in Synthesis Example 4 were followed, except for using 3.28 g of 1,1-diphenylvinylboronic acid in place of the 4-biphenylylboronic acid, to obtain 3.77 g (yield: 72%) of the desired compound.

Provenance & Evidence