Magnetic MOF-199-Catalyzed Synthesis of Benzo[4,5]imidazo[1,2-f]phenanthridines and Their Analogues by Tandem C(sp2)-C Coupling and Cyclization Followed by Aromatization

초록

Treatment of 2-(2-bromoaryl)- and 2-(2-bromovinyl)benzimidazoles with cyclohexane-1,3-diones in DMF in the presence of reusable Fe3O4@SiO2@MOF-199 along with L-proline and Cs2CO3 afforded 2,3-dihydrobenzo[4,5]imidazo[1,2-f]phenanthridin-4(1H)-ones and 2,3-dihydrobenzo[4,5]imidazo[1,2-a]quinolin-4(1H)-ones, respectively, in moderate to good yields. Such C(sp(2))-C coupled and cyclized scaffolds were aromatized to benzo[4,5]imidazo[1,2-f]phenanthridines and benzo[4,5]imidazo[1,2-a]quinolines in good yields by a one-pot sequential treatment with NaBH4, POCl3/pyridine, and DDQ.

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