Synthesis
An 500 ml four-necked flask is charged with 40 g (0,18 mol) of trans 2-[1-(4-amino]- cyclohexyl)-acetic acid ethyl ester hydrochloride and 160 ml of dichloromethane. To the resulting suspension 18,2 g (0,18 mol) of triethylamine is added. The reaction mixture is cooled to a temperature between 8-10°C and a solution of 40,0 g (0,185 mol) of di(tert-butyl)dicarbonate in 100 ml of dichloromethane is added for 1 hour with stirring under nitrogen. Then the reaction mixture is allowed to warm to a temperature between 22-25°C and stirred until the reaction proceeds. After completion of the reaction 100 g of 5% aqueous sodium carbonate is added and the phases are separated. The organic layer is extracted with 50 ml of water and after separation the organic layer is dried under Na2SO4 and the filtrate is concentrated in vacuum. The trans 2-{1-[4-(N-tert-butoxycarbonyl)-amino]-cyclohexyl}-acetic acid ethyl ester obtained is dissolved in 460 ml of tetrahydrofurane then 13,68 g (0,36 mol) of sodium borohydride is added at 25°C under nitrogen. With stirring, to the reaction mixture a solution of 24,0 g (0,18 mol) of aluminium chloride in 250 ml abs. tetrahydrofurane is added dropwise at a temperature between 18-22°C for 1 hour under nitrogen then the mixture is stirred for additional 2 hours. After completion of the reaction the mixture is cooled to a temperature between 5-10°C and 650 ml of water and 600 ml of toluene are added. Then the pH was adjusted to 3-4 by adding 40-45 ml of concentrated hydrochloric acid and the stirring was continued at a temperature between 20-25°C for 1 hour. The phases are separated, the aqueous layer is extracted with 50 ml of toluene and the combined organic layers are washed with 3×150 ml of water and dried in vacuum. In this manner 41,1 g of title compound was obtained. Yield: 94% 20. Melting point: 101-103°C.
![CarbaMic acid, N-[trans-4-(2-hydroxyethyl)cyclohexyl]-, 1,1-diMethylethyl ester Structure](https://www.chemicalbook.com/CAS/GIF/917342-29-1.gif)
