An Expeditious and Efficient Synthesis of Highly Functionalized [1,6]-Naphthyridines under Catalyst-Free Conditions in Aqueous Medium

This is the first report of an innovative, one-pot, catalyst-free, pseudo-five-component synthesis of 1,2-dihydro[1,6]naphthyridines from methyl ketones, amines, and malononitrile in ecofriendly solvent water. The protocol avoids the use of expensive catalysts, toxic organic solvents and anhydrous condition. The approach to naphthyridines presented herein offers for the first time an unprecedented coupling which leads to the construction of both the nitrogen containing rings during the synthesis without starting from any nitrogen-containing heterocycle moiety.