Multicomponent synthesis of styryl linked benzo[h]pyrazolo[3,4-b]quinoline-5,6(10H)-diones by liquid assisted grinding

Abstract

Herein we report an interesting multicomponent reaction of α,β-unsaturated aldehydes, 2-hydroxy-1,4-naphthoquinone and 5-aminopyrazoles by liquid assisted grinding. This three-component reaction provides styryl linked benzo[h]pyrazolo[3,4-b]quinoline-5,6(10H)-diones by grinding for 20–30 min in the presence of water (η = 0.25 μL mg⁻¹). The resultant three-component product has four bioactive moieties such as 1,2-naphthoquinone, pyridine, pyrazole and styryl. One-pot green reaction conditions, short reaction time, easier purification process, and good yields are the other notable features of this methodology. All the products were characterized by IR, NMR and HRMS. Furthermore, the structure was unambiguously confirmed by recording single crystal XRD of two compounds.