反应详情

12.0 g of 4-bromo-2,6-difluorophenol, 10.0 ml of (S)-(+)-2-octanol and 16.5 g of triphenylphosphine were dissolved in 300 ml of tetrahydrofuran at about 20° C. with stirring under a nitrogen atmosphere. 12.5 ml of anhydrous (max. 0.0075% of H2O) diisopropyl azodicarboxylate were subsequently added dropwise. The reaction proceeds exothermically. The rate of addition was selected in such a way that the temperature of the mixture did not exceed 45° C. The reaction solution was subsequently stirred for 2 h, and the solvent was then removed in a rotary evaporator. The crude product was purified in a mixture of chlorobutane and heptane in the ratio 1:1 over 2 l of silica gel, giving 14.5 g of 3,5-difluoro-4-(1-methylheptyloxy)bromobenzene as a clear liquid.

1. additionThe rate of addition
2. customdid not exceed 45° C
3. stirringThe reaction solution was subsequently stirred for 2 h
4. customthe solvent was then removed in a rotary evaporator
5. customThe crude product was purified in a mixture of chlorobutane and heptane in the ratio 1:1 over 2 l of silica gel