2-[Dimethylaminothiophen-2-ylmethyl]-1(3-trifluoromethylbenzyl)cyclohexanol, hydrochloride → 2-(Dimethylaminothiophen-2-ylmethyl)cyclohexanone

Participants

Reaction Steps

0.31 g (12.6 mmole) of magnesium turnings was stirred in 10 ml of ether of analysis purity. 2.46 g (12.6 mmole) of 3-chloromethylbenzotrifluoride dissolved in 10 ml of ether were added dropwise so that the reaction mixture boiled gently. After completion of the addition the reaction mixture was stirred for a further hour at RT. 2.50 g (10.5 mmole) of the 2-(dimethylaminothiophen-2-ylmethyl)cyclohexanone prepared according to stage 1 were dissolved in 10 ml of ether, added dropwise to the Grignard reagent while cooling in an ice bath, and stirred for 15 hours at RT. The reaction mixture was worked up by adding 15 ml of saturated ammonium chloride solution while cooling in an ice bath, and was extracted three times at RT with 20 ml of ether each time. The combined organic extracts were dried over sodium sulfate, filtered, and concentrated by evaporation on a rotary evaporator (500 to 10 mbar). 3.33 g of crude base (79.6% of theory) were obtained, from which a hydrochloride was precipitated according to Example 1 (3rd stage) with chlorotrimethylsilane/water in 2-butanone. The base was freed from the hydrochloride with 20 ml of water and 5 ml of ammonia solution (25 vol. %), extracted three times with 20 ml of ether each time, and the combined organic extracts were dried over sodium sulfate, filtered, and concentrated by evaporation on a rotary evaporator (500 to 10 mbar). 0.63 g of crude base (15.0% of theory) was obtained, from which 0.39 g of 2-[dimethylaminothiophen-2-ylmethyl]-1(3-trifluoromethylbenzyl)cyclohexanol, hydrochloride (8.5% of theory) was obtained according to the procedure described in Example 1 (3rd Stage) with chlorotrimethylsilane/water in 2-butanone. The hydrochloride decomposes on heating above 98° C.

Provenance & Evidence