反应详情

1-methanesulfonylpiperazine (1.1 g, 6.8 mmol) followed by a catalytic amount of AcOH (0.020 mL, 0.34 mmol) were added to a stirred solution of 5,6-dichloronicotinaldehyde (1.20 g, 6.8 mmol) in EtOH (100 mL, 1713 mmol), the mixture was stirred at room temperature for 1 h (white precipitate formed), and the resulting suspension was treated portionwise with sodium cyanoborohydride (0.43 g, 6.8 mmol) (slightly exothermic) and stirred for another 2 h. The mixture was concentrated and quenched with 1 N HCl (aq), water (10 mL each) and EtOAc (50 mL). The separated aqueous layer was extracted with ethyl acetate (2×50 mL) and the combined organic layers were washed with brine, dried over Na2SO4, and concentrated to give a crude residue which was purified with flash column chromatography (ISCO Combiflash system, pure DCM to 3% 2 M NH3/MeOH in DCM) to give 1-((5,6-dichloropyridin-3-yl)methyl)-4-(methylsulfonyl)piperazine (1.16 g, 52%) as a white solid. LCMS (API-ES) m/z 325 (M+H)+; 1H NMR (400 MHz, CDCl3) δ 8.23 (s, 1H) 7.78 (s, 1H) 3.54 (s, 2H) 3.26 (br. s., 4H) 2.80 (s, 3H) 2.57 (br. s., 4H).

1. custom(white precipitate formed)
2. stirringstirred for another 2 h
3. concentrationThe mixture was concentrated
4. customquenched with 1 N HCl (aq), water (10 mL each) and EtOAc (50 mL)
5. extractionThe separated aqueous layer was extracted with ethyl acetate (2×50 mL)
6. washthe combined organic layers were washed with brine
7. dry with materialdried over Na2SO4
8. concentrationconcentrated
9. customto give a crude residue which
10. customwas purified with flash column chromatography (ISCO Combiflash system, pure DCM to 3% 2 M NH3/MeOH in DCM)