Green one-pot three-component synthesis of 4H-chromenes in the presence of nano-kaoline/BF3/Fe3O4 as a super paramagnetic nanocatalyst

Abstract

Fused benzo-4H-pyran, namely 4H-chromene moiety, exists in several heterocyclic compounds with biological activities such as antioxidant, antibacterial, antiviral, antifungal, hypotensive, diuretic, antiallergenic, antileishmanial, anticoagulant, and antitumor. Herein, one-pot three components of aldehyde, malononitrile, and enolizable compounds in the presence of nano-kaoline/BF3/Fe3O4 catalytic system to improve the 4H-chromenes via domino Knoevenagel-Michael-cyclization coupling reaction are reported. The advantages of this protocol involve high yield of products, use of solvent-free condition, easy experimental work-up system, low reaction times, recyclable catalyst, and green process, which privilege it as an alternative to other analogous synthetic procedures. The structure of synthesized 4H-chromenes was elucidated by FT-IR, 1H NMR, and 13C NMR.