反应详情

A solution of 11.6 g (containing 31 mmol) of crude trans-(4-Hydroxy-cyclohexyl)-methyl-carbamic acid 3,4-difluoro-phenyl ester in 110 ml of 1,4-dibromobutane was treated with 3.16 g (9.3 mmol) tetrabutylammonium hydrogen sulfate and 200 ml of aqueous 50% NaOH and stirred for 2.5 days at RT. The reaction was extracted (CH2Cl2 2×). The organic phase was dried over Na2SO4, evaporated and purified by flash silica gel column (first with hexane to remove the dibromobutane and then hexane/EtOAc 1:1) to yield 4.06 g (31%) of trans-[4-(4-bromo-butoxy)-cyclohexyl]-methyl-carbamic acid 3,4-difluoro-phenyl ester, MS: 420 (M, 1Br).

1. extractionThe reaction was extracted (CH2Cl2 2×)
2. dry with materialThe organic phase was dried over Na2SO4
3. customevaporated
4. custompurified by flash silica gel column (first with hexane
5. customto remove the dibromobutane