Ultrasound‐promoted novel route to triazabenzo[b]cyclopenta[lm]fluorenes: An efficient NiFe₂O₄@SiO₂–SO₃H nanocatalyst‐assisted green synthesis

A series of new triazabenzo[b]cyclopenta[lm]fluorene scaffolds have been synthesized from 1,2‐phenylenediamines, isothiocyanates and ninhydrin via a heterogeneous and efficient NiFe 2 O 4 @SiO 2 –SO 3 H nanoparticle‐catalysed, ultrasonic irradiation‐assisted, eco‐friendly protocol. The NiFe 2 O 4 @SiO 2 –SO 3 H nanopowder has been synthesized and thoroughly characterized by FTIR, powdered XRD, FESEM, HRTEM, EDX and N 2 adsorption analysis. The most desirable agenda of our methodology is to evolve an eco‐friendly green protocol with minimum reaction time and easy reaction condition. A new and efficient catalyst, broad scope in substrate variation, very high yield percentages, use of green solvent and very short reaction time are the crucial advantages of our methodology.