Highly Stereoselective Synthesis of 2-Aminobenzylidene Derivatives by a Convergent 3-Component Approach

An one-pot stereoselective synthesis of 2-aminobenzylidene derivatives from readily available 5-nitro/cyano-activated 2-halobenzaldehydes (2-chloro-5-nitrobenzaldehyde, 2-bromo-5-nitrobenzaldehyde, 2-fluoro-5-nitrobenzaldehyde, 5-cyano-2-fluorobenzaldehyde), the active methylidene compounds (cyanoacetamide and ethyl cyanoacetate), and secondary cycloamines via a novel parallel convergent Knoevenagel–nucleophilic aromatic substitution and nucleophilic aromatic substitution–Knoevenagel condensation cascade approach under mild conditions has been developed with high stereoselectivity and in 52–88% yields.