[C:1]1([CH3:17])[CH:6]=[CH:5][C:4]([C:7]2[O:8][C:9]3[CH:15]=[CH:14][C:13]([NH2:16])=[CH:12][C:10]=3[N:11]=2)=[CH:3][CH:2]=1.C(O)(=O)C.[CH:22](=O)[C:23]1[CH:28]=[CH:27][N:26]=[CH:25][CH:24]=1.C(O[BH-](OC(=O)C)OC(=O)C)(=O)C.[Na+]>ClCCCl.ClCCl>[N:26]1[CH:27]=[CH:28][C:23]([CH2:22][NH:16][C:13]2[CH:14]=[CH:15][C:9]3[O:8][C:7]([C:4]4[CH:3]=[CH:2][C:1]([CH3:17])=[CH:6][CH:5]=4)=[N:11][C:10]=3[CH:12]=2)=[CH:24][CH:25]=1To 2-p-tolylbenzo[d]oxazol-5-amine (500 mg, 2.32 mmol) in 1,2-dichloroethane (20 mL) at room temperature was added acetic acid (142 μL, 2.32 mmol) and isonicotinaldehyde (222.5 μL, 2.29 mmol) and the mixture was stirred for 1 h. Sodium triacetoxyborohydride (707 mg, 3.35 mmol) was then added and the mixture was stirred at room temperature for 24 h. The mixture was then diluted with dichloromethane and the organic layer was washed with saturated aqueous NaHCO3. The combined organic layers were dried over anhydrous MgSO4 and evaporated. The resulting solid was purified by column chromatography eluting with ethyl acetate:hexanes 20:80 to afford 328 mg (47%) of the title compound (LCMS RT=6.27 min, MH+ 316.1)
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