Facile Route to the Synthesis of 1,3-Diazahetero-Cycle-Fused [1,2-a]Quinoline Derivatives via Cascade Reactions

[Image: see text] A one-step protocol without transition-metal catalysts with simple post-treatment for the synthesis of 1,3-diazaheterocycle-fused [1,2-a]quinoline derivatives via the cascade reaction of 2-fluorobenzaldehyde (1) and heterocyclic ketene aminals (2) was developed. In the one-step cascade reaction, C=C and C–N bonds were constructed, and the targeted compound can be efficiently obtained by filtering without column chromatography. This protocol describes a valuable route to concisely and feasibly obtain 1,3-diazaheterocycle-fused [1,2-a]quinoline derivatives. The synthetic methodology is particularly attractive because of the following features: low-cost solvent, mild temperature, atom economy, high yield, and potential biological activity of the product.