[NH2:1][C:2]1[C:3]2[N:4]([C:8]([CH3:12])=[C:9]([CH3:11])[N:10]=2)[CH:5]=[CH:6][CH:7]=1.[CH2:13]([C:15]1[CH:22]=[CH:21][CH:20]=[C:19]([CH2:23][CH3:24])[C:16]=1[CH:17]=O)[CH3:14].[BH3-]C#N.[Na+].[OH-].[Na+]>CO.[Cl-].[Cl-].[Zn+2].CCCCCC>[CH3:11][C:9]1[N:10]=[C:3]2[C:2]([NH:1][CH2:17][C:16]3[C:15]([CH2:13][CH3:14])=[CH:22][CH:21]=[CH:20][C:19]=3[CH2:23][CH3:24])=[CH:7][CH:6]=[CH:5][N:4]2[C:8]=1[CH3:12]8-amino-2,3-dimethyl-imidazo[1,2-a]pyridine (0.33 g, 2.0 mmol) and 2,6-diethylbenzaldehyde (0.36 g, 2.2 mmol) were dissolved in methanol (7 ml). ZnCl2 (0.30 g, 2.2 mmol) and subsequently NaBH3CN (0.14 g, 2.2 mmol) in small portions were added and the mixture was refluxed under argon for 3 hours, cooled and then poured over an aqueous 1M NaOH solution (10 ml). The resultant yellow suspension was extracted with DCM (3×25 ml) and the combined organic solutions were washed with brine, dried over Na2SO4 and then removed. The oily residue (0.4 g) was purified by flash chromatography (DCM-EtOAc 0%-20% EtOAc) to give 0.34 g. Treatment of this oily product with hexane (2 ml) afforded 0.14 g (23%) as off-white crystals.
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