反应详情

52.4 g (about 0.22 mol) of crude 7,8-difluoro-2-pentylchroman are initially introduced in 400 ml of THF, and 150.7 ml (0.24 mol) of n-BuLi (15% soln. in hexane) are added at −70° C. After 3 h at this temperature, 26.8 ml (0.24 mol) of trimethyl borate are added dropwise, and the batch is warmed to room temperature. 55 ml of dilute acetic acid (about 30%) are added, and 57 ml of hydrogen peroxide soln. (35%) are carefully added to the batch. When the addition is complete, the mixture is stirred for 17 h at room temperature. Water is added, and the batch is acidified using HCl. The solution is extracted a number of times with MTBE, and the combined organic phases are washed successively with water, sat. sodium chloride soln. and ammonium iron(II) sulfate soln. The solution is dried using sodium sulfate and concentrated to dryness. The crude product is purified by column chromatography (SiO2, n-heptane:MTBE=2:1).

1. addition(35%) are carefully added to the batch
2. additionWhen the addition
3. extractionThe solution is extracted a number of times with MTBE
4. washthe combined organic phases are washed successively with water, sat. sodium chloride soln
5. customThe solution is dried
6. concentrationconcentrated to dryness
7. customThe crude product is purified by column chromatography (SiO2, n-heptane:MTBE=2:1)