A solution of 1.5 mmol trichloromethyl-chloroformate (diphosgene) in 20 ml CH2Cl2 was treated at 0° C. with 3 mmol of 2,4-difluoro-phenol and 3 mmol quinoline and then stirred for 3 h at room temperature. The reaction was then cooled (0° C.) and a solution of 1 mmol [4-(4-Bromo-butoxy)-cyclohexyl]-methyl-amine (privously prepared from trans-[4-(4-Bromo-butoxy)-cyclohexyl]-methyl-amine hydrochloride by extraction with aqueous NaHCO3/EtOAc) and 2.5 mmol pyridine in 3 ml CH2Cl2 was added. The reaction was stirred over night at room temperature, evaporated to give crude trans-[4-(4-Bromo-butoxy)-cyclohexyl]-methyl-carbamic acid 2,4-difluoro-phenyl ester which was used directly in the next step, see Example 12.39-12.44.
