反应详情

tert-Butyl(chloro)dimethylsilane (6.42 g, 42.6 mmol) was added to a solution of 2,6-difluoro-4-hydroxybenzoic acid (3.09 g, 17.8 mmol) in THF (50 mL), followed by the addition of N,N-diisopropylethylamine (9.19 mL, 51.5 mmol) over 5 min. After stirring at rt for 10 min the solution was concentrated in vacuo. Purification by gradient column chromatography, eluting with 10-50% solvent A in solvent B (A=DCM, B=DCM:MeOH:AcOH 95:5:1) yielded 2,6-difluoro-4-(tert-butyldimethylsilyloxy)benzoic acid (615 mg). This material was dissolved in THF (20 mL), borane-THF complex (1.0M in THF, 6.4 mL, 6.4 mmol) was added and the solution stirred at rt for 4 h. Further borane-THF complex (1.0M in THF, 6.4 mL, 6.4 mmol) was added and the solution stirred at rt for 18.5 h before concentration in vacuo. Purification by gradient column chromatography, eluting with 0-10% EtOAc in iso-hexane yielded 2,6-difluoro-4-(tert-butyldimethylsilyloxy)benzyl alcohol (470 mg). The title compound (533 mg, 0.90 mmol) was subsequently prepared from 2,6-difluoro-4-(tert-butyldimethylsilyloxy)benzyl alcohol (356 mg, 1.30 mmol) and (IntA1) (289 mg) using the methods of (77).

1. concentrationwas concentrated in vacuo
2. customPurification by gradient column chromatography
3. washeluting with 10-50% solvent A in solvent B (A=DCM, B=DCM:MeOH:AcOH 95:5:1)