Recyclable nanoparticulate copper mediated synthesis of naphthoxazinones in PEG-400: a green approach

An efficient methodology employing copper nanoparticles for the preparation of 2-naphthol condensed 1,3-oxazinone derivatives employing one-pot condensation reaction in the presence of K2CO3 and copper nanoparticles in PEG-400 is described which offers several advantages, viz. high yields, clean reaction, short reaction times, recyclability of the catalyst and simple workup procedure. PEG-400 was found to be the best solvent out of a range of solvents examined for this scheme. Moreover, PEG could stabilize the nanoparticles from oxidation and thus could increase the catalyst efficiency by escalating the TON (Turn over Number) and TOF (Turn over Frequency) of the catalyst, making the protocol greener, eco-friendly and environmentally benign.