L-arginine-functionalized magnetic nanoparticles as a recyclable organocatalyst for synthesis of chromenes

A practical, convenient, and cheap methodology is developed for the synthesis of a series of chromene derivatives via cyclocondensation of α- or β-naphthol, malononitrile and aromatic aldehydes, in the presence of L-arginine-immobilized magnetic nanoparticles, under ultrasound irradiation, in high yields. This catalyst can be easily separated from the reaction by an external magnet and recycled four times without its activity loss. This methodology has shown shorter reaction times when compared with conventional thermal heating.Chromenes constitute one of the major classes of naturally occurring compounds. The basic structural skeleton of these compounds is an ordinary characteristic of polyphenols(1) found in tea, fruits, vegetables and red wine. Fused chromenes exhibit antimicrobial,(2) mutagenicitical, antiviral, antiproliferative, antitumoral properties and be employed as cosmetics and pigments. These compounds can be used as potential biodegradable agrochemicals.(3)