2-Bromotoluene → Methyl 4-(2-methylphenyl)benzoate

Participants

Reaction Conditions

Reaction Steps

A 2 L three-necked 24/40 round-bottom flask equipped with a mechanical stirrer, a 500 mL constant pressure addition funnel with a nitrogen inlet at the top, and a septum was flame dried, cooled and then charged with a solution of 70.00 g (0.409 mol) of o-bromotoluene in 350 mL of anhydrous tetrahydrofuran under a nitrogen atmosphere. The solution was stirred and cooled to -78° C. and 481 mL (0..818 mol) of a 1.7M solution of t-butyllithium in pentane was added via the addition funnel over 45 minutes. When the addition was complete, the cooling bath was removed and the reaction mixture was stirred for 45 minutes and allowed to warm to room temperature. The dropping funnel was next charged with 409 mL (0.409 mol) of a 1.0M solution of zinc chloride in diethylether which was added to the reaction mixture over a 20 minute period. A separate 2 L three-necked 24/40 round-bottom flask equipped with a mechanical stirrer, a nitrogen inlet and a septum, was flame dried, cooled and then charged with 8.93 g (13.7 mmol) of bis(triphenylphosphine)nickel(II) chloride, 58.71 g (0.273 mol) of methyl-2-bromobenzoate and 450 mL of anhydrous tetrahydrofuran under a nitrogen atmosphere. The suspension of the tolylzinc chloride was then transferred to the second flask via a wide diameter cannula. The reaction mixture was stirred an additional 45 minutes at room temperature, then most of the tetrahydrofuran was removed on a rotary evaporator. The resulting oil was partitioned between ethyl acetate (500 mL) and water (300 mL). The organic layer was washed successively with water, 5% hydrochloric acid, water, and brine, then dried (MgSO4), filtered and evaporated. The residual oil was purified on a Waters Prep 500 HPLC (2 silica packs) eluted with 1.5% ethyl acetate-hexane in eleven separate runs (mixed fractions recycled, 10 g per injection). The purified fractions were evaporated and freed of residual solvent in vacuo to afford 53.42 g (74%) of a colorless oil which had.

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