反应详情

To 3-bromo-5-methylbenzyl bromide (Step A above) (5.49 g, 20 mmole) in glacial acetic acid (9.0 mL) and H2O` (9 mL) was added hexamethylenetetramine (4.50 g, 32 mmole) and the reaction was stirred at reflux for 2 hours. Concentrated HCl (7.0 mL) was added and the mixture was refluxed an additional 15 minutes. After cooling to room temperature, the reaction mixture was diluted with H2O (75 mL) and extracted with ether (150 mL). The ether layer was washed with H2O (3×25 mL), 10% NaHCO3 (2×50 mL) and dried over MgSO4. The ether was removed under vacuum and the residue was chromatographed on silica gel eluting with hexane and 10% Et2O/hexane to yield 3-bromo-5-methylbenzaldehyde (2.80 g) as a light yellow oil which solidified upon standing. MS and NMR were consistent with the desired structure.

1. temperatureat reflux for 2 hours
2. temperaturethe mixture was refluxed an additional 15 minutes
3. extractionextracted with ether (150 mL)
4. washThe ether layer was washed with H2O (3×25 mL), 10% NaHCO3 (2×50 mL)
5. dry with materialdried over MgSO4
6. customThe ether was removed under vacuum
7. customthe residue was chromatographed on silica gel eluting with hexane and 10% Et2O/hexane