Thionyl Chloride → 4-Bromo-1-chloro-2-(chloromethyl)benzene

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

5-Bromo-2-chlorobenzyl alcohol (3.0 g) was dissolved in toluene (30 ml), and added thereto were thionyl chloride (2.35 ml) and pyridine (two drops), and the mixture was heated under stirring at 100° C. for 2 hours. The mixture was cooled, washed with a saturated aqueous sodium hydrogen carbonate solution and brine, and dried over sodium sulfate. The solvent was evaporated under reduced pressure to give 5-bromo-2-chlorobenzyl chloride (3.34 g) as pale brown oil, which was used in the subsequent step without further purification. (2) The above 5-bromo-2-chlorobenzyl chloride (3.34 g) was dissolved in N, N-dimethylformamide (30 ml), and added thereto was potassium phthalimide (2.63 g), and the mixture was heated under stirring at 70° C. for 3 hours. The reaction solution was poured into water, and the mixture was extracted with ethyl acetate. The extract was washed with brine, and dried over sodium sulfate. The solvent was evaporated under reduced pressure, and the residue was crystallized from diisopropyl ether to give 5-bromo-2-chloro-1-(phthalimid-2-ylmethyl)benzene (3.33 g) as colorless crystals. APCI-Mass m/Z 350/352 (M+H). (3) The above 5-bromo-2-chloro-1-(phthalimid-2-ylmethyl)benzene (4.3 g) was dissolved in acetic acid (43 ml), and added thereto was zinc powder (8.02 g), and the mixture was heated at reflux for 3 days. The mixture was cooled and diluted with chloroform and it was basified with an aqueous sodium hydroxide solution. The organic layer was dried over sodium sulfate, and the solvent was evaporated under reduced pressure. The residue was purified by silica gel column chromatography (hexane:ethyl acetate=6:1-4:1) to give the desired 5-bromo-2-chloro-1-(1-oxo-2-isoindolinylmethyl)benzene (1.39 g) as colorless powder. APCI-Mass m/Z 336/338 (M+H).

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