Triethylamine → 2-(3-Chlorophenyl)-4,5-dihydro-4-[(4-methylphenyl)methyl]oxazole

Participants

Reaction Steps

A solution of 1.75 g (10 millimoles) of 3-chlorobenzoyl chloride in 15 ml of tetrahydrofuran was added with ice cooling and stirring to a 100 ml egg-plant-shaped flask containing 1.61 g (10 millimoles) of 2-amino-3-(4-methyl-phenyl)-1-propanol, 1.01 g (10 millimoles) of triethylamine and 30 ml of tetrahydrofuran over the course of 30 minutes. The mixture was further stirred at 20° C. for 3 hours. The resulting triethylamine hydrochloride was removed by a glass filter, and the filtrate was concentrated under reduced pressure. Thionyl chloride (5 ml; 68 millimoles) was added all at once to a 100 ml eggplant-shaped flask containing this concentrate and 30 ml of benzene. With stirring, the mixture was refluxed for 3 hours. The reaction mixture was cooled to room temperature, and concentrated under reduced pressure. The concentrate was dissolved in 100 ml of ethyl acetate, washed with a saturated aqueous solution of sodium hydrogen carbonate, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. A 100 ml eggplant-shaped flask containing this concentrate and 30 ml of ethanol was heated to 70° C. over an oil bath with stirring, and 15 ml of a 3 % aqueous solution of sodium hydroxide was added over 10 minutes. The mixture was further stirred at 70° C. for 20 minutes, and concentrated under reduced pressure. Benzene (100 ml) was added to the concentrate, and the mixture was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The concentrate was purified by silica gel column chromatography (mobile phase: hexane/ethyl acetate=7/3) to give 2-(3-chlorophenyl)-4-(4-methylbenzyl) -2-oxazoline (compound No. 108) as a yellow viscous oil. Yield 1.7 g (59.5 %).

Provenance & Evidence