反应详情

To a stirred solution of 1-(2-trimethylsilylethoxymethyl)-2-formyl-benzimidazole (4.26 g, 15.4 mmol) in dry MeOH (50 mL) was added a solution of 8-amino-5,6,7,8-tetrahydroquinoline (2.20 g, 14.8 mmol) in dry MeOH (20 mL) and the mixture stirred for 2 h at room temperature under an argon atmosphere. The reaction mixture was concentrated under reduced pressure and the resultant residue analyzed by 1H NMR to confirm imine formation. The residue was re-dissolved in dry MeOH (80 mL) and to the resultant solution was added sodium borohydride (1.17 g, 30.8 mmol). The mixture was stirred for 5 h, concentrated in vacuo and diluted with CH2Cl2 (100 mL) and saturated aqueous NaHCO3 (125 mL). The phases were separated and the aqueous layer was extracted with CH2Cl2 (2×75 mL). The combined organic extracts were dried (Na2SO4), filtered and concentrated in vacuo. Purification of the crude material through a plug of silica gel (CH2Cl2/MeOH 96:4) afforded the desired amine (5.91 g, 98%) as an orange oil. 1H NMR (CDCl3) δ −0.07 (s, 9H), 0.90 (t, 2H, J=9 Hz), 1.72-1.83 (m, 2H), 1.95-2.01 (m, 1H), 2.76-2.85 (m, 2H), 3.54 (t, 2H, J=9 Hz), 4.33 (m, 2H), 5.68 (d, 1H, J=12 Hz), 5.75 (d, 1H, J=12 Hz), 7.05-7.09 (m, 1H), 7.25-7.30 (m, 2H), 7.38 (d, 1H, J=9 Hz), 7.44-7.46 (m, 1H), 7.71-7.73 (m, 1H), 8.36-8.38 (m, 1H).

1. concentrationThe reaction mixture was concentrated under reduced pressure
2. dissolutionThe residue was re-dissolved in dry MeOH (80 mL) and to the resultant solution
3. stirringThe mixture was stirred for 5 h
4. concentrationconcentrated in vacuo
5. additiondiluted with CH2Cl2 (100 mL) and saturated aqueous NaHCO3 (125 mL)
6. customThe phases were separated
7. extractionthe aqueous layer was extracted with CH2Cl2 (2×75 mL)
8. dry with materialThe combined organic extracts were dried (Na2SO4)
9. filtrationfiltered
10. concentrationconcentrated in vacuo
11. customPurification of the crude material through a plug of silica gel (CH2Cl2/MeOH 96:4)