Iodine → Benzhydrol

Participants

Reaction Steps

A Grignard reagent was prepared from 1-bromo-4-(ethylthio)benzene (1.1 g), magnesium (0.12 g), a catalytic amount of iodine and tetrahydrofuran (5 mL). To the Grignard reagent solution was added a solution of 2-(methoxymethoxy)-benzaldehyde (0.56 g) in tetrahydrofuran (12 mL), and the mixture was stirred at 65% for 10 minutes. After cooling to ambient temperature, a saturated aqueous ammonium chloride solution (5 mL) and water (20 mL) were added to the reaction mixture, and the mixture was extracted with ethyl acetate (80 mL). The extract was washed with water (20 mL) and brine (20 mL), dried over anhydrous sodium sulfate, then the solvent was removed under reduced pressure. The residue was purified by column chromatography on silica gel (eluent: hexane/ethyl acetate=4/1) to give a diphenylmethanol compound (0.91 g). The obtained diphenylmethanol compound (0.90 g) was dissolved in dichloromethane (15 mL). To the solution was added a Dess-Martin reagent (1,1,1-tri(acetyloxy)-1,1-dihydro-1,2-benziodoxol-3(1H)-one) (1.5 g), and the mixture was stirred at 25° C. for 26 hours. To the reaction mixture were added diethyl ether (75 mL) and 1 mol/L aqueous sodium hydroxide solution (30 mL), the mixture was stirred vigorously, and the organic layer was separated. The organic layer was washed with 1 mol/L aqueous sodium hydroxide solution (30 mL), water (30 mL, 3 times) and brine (30 mL), dried over anhydrous sodium sulfate, and the solvent was removed under reduced pressure. The residue was purified by column chromatography on silica gel (eluent: hexane/ethyl acetate=15/1–9/1) to afford a ketone compound (0.82 g). A mixture of the obtained ketone compound (0.81 g), p-toluene-sulfonic acid monohydrate (0.10 g) and methanol (14 mL) was stirred at 60° C. for 4 hours. After cooling to ambient temperature, the reaction mixture was concentrated under reduced pressure. The residue was purified by column chromatography on silica gel (eluent: hexane/ethyl acetate=15/1) to give a deprotected compound (0.69 g). The obtained deprotected compound (0.68 g) was dissolved in tetrahydrofuran (11 mL), triethylamine (0.41 mL) and methyl chloroformate (0.22 mL) were added to the solution, and the mixture was stirred at 25° C. for 1 hour. Furthermore, triethylamine (0.11 mL) and methyl chloroformate (0.061 mL) were added to the reaction mixture, and the mixture was stirred for 30 minutes. The reaction mixture was filtered, and the filtrate was concentrated under reduced pressure. The residue was dissolved in tetrahydrofuran (14 mL) and water (7 mL), sodium borohydride (0.40 g) was added to the solution, and the mixture was stirred at 25° C. for 7 hours. To the reaction mixture was added dropwise 1 mol/L hydrochloric acid (15 mL), and the mixture was extracted with ethyl acetate (75 mL). The extract was washed with water (20 mL), a saturated aqueous sodium hydrogen carbonate solution (20 mL) and brine (20 mL), dried over anhydrous sodium sulfate, and the solvent was removed under reduced pressure. The residue was purified by column chromatography on silica gel (eluent: hexane/ethyl acetate=8/1) to give 2-(4-ethylthiobenzyl)phenol (0.62 g).

Provenance & Evidence