Expeditious synthesis of diverse spiro fused quinoxaline derivatives using magnetically separable core–shell CoFe 2 O 4 @SiO 2 ‐SO 3 H nanocatalyst under ultrasonication

A magnetically separable core–shell CoFe 2 O 4 @SiO 2 ‐SO 3 H nanocatalyst has been successfully exploited as a heterogeneous acid catalyst in the synthesis of diversely substituted biologically important spiro fused pyrrolo/indolo[1,2‐ a ]quinoxaline derivatives through the condensation of N ‐(2‐aminophenyl)pyrroles/indoles and various cyclic conjugated 1,2‐diones in ethanol under ultrasonic irradiation. Room temperature synthesis, short reaction time, wide substrate scope, good to excellent yield of products and use of a magnetically separable and recyclable nanocatalyst make this method attractive and practicable.