Cascade Reaction of 1,1-Enediamines with 2-Benzylidene-1-indene-1,3(2)-diones: Selective Synthesis of Indenodihydropyridine and Indenopyridine Compounds.

A concise and environmentally friendly route for the synthesis of diverse indenodihydropyridines () via a cascade reaction of 1,1-eneamines () with benzylidene-1-indene-1,3(2)-diones (BIDs) () in ethanol media was developed. The targeted compounds were efficiently obtained by only filtration without any further post-treatment. In the one-step cascade reaction, C-C and C-N bonds were constructed. In addition, when 1,4-dioxane was used as a solvent and the mixture of 1,1-eneamines () was refluxed with benzylidene-1-indene-1,3(2)-diones (BIDs) () for about 12 h, indenopyridine compounds () were produced. Two kinds of indenopyridine derivatives - resulted from alternative solvents and temperatures. The reaction had the following features: mild temperature, atom economy, high yields, and potential biological activity of the product.