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.