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

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