2-(2-Bromoaryl)imidazoles react with cyclohexane-1,3-diones in the presence of a catalytic amount of recyclable Fe 3 O 4 @SiO 2 @MOF-199 and a base to give the corresponding C–C coupled and cyclized products 6,7-dihydroimidazo[1,2- f ]phenanthridin-8(5 H )-ones in high yields. The magnetic MOF catalyst could be easily recovered and reused four times without any significant loss of catalytic activity. The coupled and cyclized scaffolds were aromatized to imidazo[1,2- f ]phenanthridines in high yields by a one-pot sequential procedure including reduction, dehydration, and oxidation. The present protocol could be applied to the synthesis of Zephycandidine A, which is known to exhibit anti-tumor activity.

Magnetic Cu-MOF-74 (Fe 3 O 4 @SiO 2 @Cu-MOF-74) was synthesized for the first time by grafting MOF-74 (copper as the metal center) on the surface of core-shell magnetic carboxyl-functionalized silica gel (Fe 3 O 4 @SiO 2 -COOH), which was prepared by coating core Fe 3 O 4 nanoparticles with hydrolyzed 2-(3-(triethoxysilyl)propyl)succinic anhydride and tetraethyl orthosilicate. The structure of Fe 3 O 4 @SiO 2 @Cu-MOF-74 nanoparticles was characterized by Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and transmission electron microscopy (TEM). The prepared Fe 3 O 4 @SiO 2 @Cu-MOF-74 nanoparticles could be applied as a recyclable catalyst to the synthesis of N-fused hybrid scaffolds. 2-(2-Bromoaryl)imidazoles and 2-(2-bromovinyl)imidazoles were coupled and cyclized with cyanamide in DMF in the presence of a catalytic amount of Fe 3 O 4 @SiO 2 @Cu-MOF-74 along with a base to give imidazo[1,2- c ]quinazolines and imidazo[1,2- c ]pyrimidines, respectively, in good yields. The Fe 3 O 4 @SiO 2 @Cu-MOF-74 catalyst could be easily recovered by a super magnetic bar and recycled more than four times while almost maintaining catalytic activity.

2‐(2‐Bromoaryl)indoles react with 2‐methoxybenzimidazoles in DMF in the presence of a catalytic amount of recyclable Fe3O4@SiO2@MOF‐199 along with K2CO3 to afford a series of benzo[4,5]imidazo[1,2‐a]indolo[1,2‐c]quinazolines in good yields. The reaction applies to a broad scope of 2‐(2‐bromoaryl)indoles containing electron‐donating or ‐withdrawing substituents on bromophenyl and indole moieties, and alkyl substituents at 3‐position of indole moiety. A reaction pathway involving a copper‐catalyzed Ullmann‐type C (sp2)‐N coupling and an addition‐elimination nucleophilic aromatic substitution via Meisenheimer complex followed by cyclocondensation is proposed for this catalytic process. The Fe3O4@SiO2@MOF‐199 catalyst could be recovered and reused several times without any change of catalytic activity.

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(sp2)−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.