To a stirred solution of N-(tert-butoxycarbonyl)-N-(2-pyridinylmethyl)-N′-(5,6,7,8-tetrahydro-8-quinolinyl)-1,4-benzenedimethanamine (174 mg, 0.38 mmol) in dry MeOH (5 mL) was added 2-imidazolecarboxaldehyde (75 mg, 0.78 mmol) and sodium cyanoborohydride (55 mg, 0.88 mmol) and the mixture was stirred for 40 h. The reaction mixture was concentrated in vacuo and partitioned between CH2Cl2 (30 mL) and aqueous 1 N sodium hydroxide (30 mL). The aqueous layer was washed with CH2Cl2 (2×20 mL) and the combined organic extracts washed with brine (30 mL), dried (MgSO4), filtered and concentrated in vacuo. Purification of the crude product by column chromatography on silica gel (CH2Cl2/MeOH, 95:5) afforded the imidazole derivative (48 mg, 24%) as a clear oil.
