Sodium Bicarbonate → (E)-5-bromo-alpha-[2-(3,4-dichlorophenyl)ethenyl]-2-methoxy-3-pyridinemethanol

関与物質

反応条件

反応手順

A solution of 60.6 g of 3,5-dibromo-2-methoxypyridine in 900 ml of anhydrous ether was stirred under nitrogen and cooled to -78° C. to give a thick slurry. Efficient stirring was used to prevent the solid starting material from adhering to the wall of the reaction vessel. While the temperature was maintained below -65° C., 85 ml of 2.67M n-butyllithium/hexane was added dropwise. The reaction mixture was homogeneous upon completion of the addition and it was stirred for 15 minutes at -78° C. Then, a solution of 45.6 g of 3,4-dichlorocinnamaldehyde in 200 ml of anhydrous tetrahydrofuran was added dropwise while keeping the temperature below -65° C. When the addition was complete, 100 ml of aqueous saturated sodium bicarbonate solution was added to the cold reaction mixture. It was then allowed to warm to about -40° C. and then partitioned between ether and aqueous saturated sodium bicarbonate solution. The aqueous layer was extracted with ether and the combined ether layers were washed with aqueous saturated sodium chloride solution, dried over potassium carbionate, filtered and concentrated to leave a pale yellow solid. This was recrystallized from a mixture of 2-propanol/ethyl acetate/hexane (1:3:5) to give (E)-5-bromo-α-[2-(3,4-dichlorophenyl)ethenyl]-2-methoxy-3-pyridinemethanol melting at about 149°-150° C.

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