Benzyl Bromide → 3-Benzyloxy-4-methylbenzoic acid benzyl ester

関与物質

反応手順

K2CO3 (18.1 g, 131.2 mmol) was added to a stirred solution of 3-hydroxy-4-methyl-benzoic acid (5 g, 33 mmol) in DMF (50 mL) followed by benzyl bromide (11.8 g, 69 mmol) and the resulting mixture was stirred at room temperature overnight. The reaction mixture was filtered, the filterate was diluted with water and extracted with EtOAc. The organic layer was collected, dried over sodium sulfate and concentrated under reduced pressure to afford 11.3 g (crude) of 3-benzyloxy-4-methyl-benzoic acid benzyl ester which was such taken for the next step without purification. NaOH (4.0 g, 102 mmol) was added to a stirred solution of 3-benzyloxy-4-methyl-benzoic acid benzyl ester (11.3 g, 34 mmol) in a mixture of MeOH (50 mL) and H2O (50 mL), stirring was continued at ambient temperature for 2 hrs. The reaction mixture was concentrated under reduced pressure Cold water was then added and acidified it with 10% aqueous HCl, the precipitate was collected to afford 7.21 g (87.8% Yield) of 3-benzyloxy-4-methyl-benzoic acid. A mixture of 3-benzyloxy-4-methyl-benzoic acid (7.21 g, 29.7 mmol) in thionyl chloride (50 mL) was stirred at 79° C. for 4 hrs. The reaction mixture was concentrated under reduced pressure to afford 7.75 g (crude) of 3-benzyloxy-4-methyl-benzoyl chloride. A solution of 3-benzyloxy-4-methyl-benzoyl chloride (7.75 g) in THF (10 mL) was poured to cold aqueous solution of ammonia (50 mL) with stirring, The precipitate was collected to afford 6.7 g (94% Yield) of 3-benzyloxy-4-methyl-benzamide. A solution of 3-benzyloxy-4-methyl-benzamide (3.0 g, 12.4 mmol) in pyridine (4 mL) was cooled to −30° C. Imidazole (1.68 g, 24.8 mmol) followed by POCl3 (2.64 g, 49.6 mmol) were added to the cold solution with stirring and the reaction was continued at the same temperature for 30 minutes. The reaction mixture was diluted with ethyl acetate. The organic layer was washed with water followed by 110% aqueous HCl solution. The organic layer separated was dried over sodium sulfate and concentrated under reduced pressure to afford 2.46 g (89% Yield) of 3-benzyloxy-4-methyl-benzonitrile. Pd/C (476 mg) was added to a stirred solution of 3-benzyloxy-4-methyl-benzonitrile (2.46 g, 11.0 mmol) in MeOH (25 mL) in an inert atmosphere and stirring was continued under H2 gas atmosphere at ambient temperature, overnight. The reaction mixture was filtered through celite. The filtrate collected was concentrated under reduced pressure to afford 1.367 g (93.6% Yield) of 3-hydroxy-4-methyl-benzonitrile.

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