反应详情

To a solution of 6.2 g (19.85 mmol) of the title A compound, t-butyl 4-(2,4-difluorobenzyl)piperazine-1-carboxylate in 50 mL of DCM at 0° C. is added 15 mL of trifluoroacetic acid. The reaction mixture is warmed to RT and stirred for 1 h, and 10 mL of 1N aqueous sodium hydroxide (NaOH) are added. The mixture is extracted with 2×100 mL of DCM and the organic layer is washed with water, dried over anhydrous MgSO4 and evaporated to dryness in vacuo. The residue is dissolved in a mixture of DCM-Et2O and two equivalents of HCl in Et2O are added, the precipitate solid is collected by filtration and washed with acetone to afford 4-(2,4-difluorobenzyl)piperazine dihydrochloride as a white solid: m.p=237° C. LC/MS (M+1=213.1). 1H NMR (DMSO-d6, 400 MHz) δ 3.44 (m, 8H), 4.39 (s, 2H), 7.25 (dt, 1H, J=8.4 Hz and 1.6 Hz), 7.43 (dt, 1H, J=9.2 Hz and 2.0 Hz), 7.84 (dd, 1H, J=15.2 Hz and 8.4 Hz), 9.84 (br s, NH). Anal. calculated for (C11H14F2N2, 2HCl+0.25H2O) C, 45.61; H, 5.74; Cl, 24.48; F, 13.12; N, 9.67; O, 1.38. Found C, 45.56; H, 5.90; N, 9.68.

1. extractionThe mixture is extracted with 2×100 mL of DCM
2. washthe organic layer is washed with water
3. dry with materialdried over anhydrous MgSO4
4. customevaporated to dryness in vacuo
5. additionare added
6. filtrationthe precipitate solid is collected by filtration
7. washwashed with acetone