A green route for the synthesis of 2-amino-5,10-dioxo-4-aryl-5,10-dihydro-4H-benzo[g]chromene-3-carbonitriles using L-proline as a basic organocatalyst

4H-Chromene derivatives were detected in natural compounds1 and demonstrated pharmacological and biological activities.2 Some synthetic approaches to 2-amino-4H-chromene derivatives via three components one-pot reactions involved such catalysts as triethylbenzylammonium chloride, DMF/AcOH, Et3N, DBU, ionic liquids, NH4OAc, KF, urea, and some the others reagents in literature.3In this paper, a new procedure for the one pot synthesis of 2-amino-5,10-dioxo-4-aryl-5,10-dihydro-4H-benzo[g]chromene-3-carbonitriles using aryl aldehydes, 2-hydroxy-1,4-naphthoquinone and malononitrile in the presence of L-proline in refluxing ethanol is described (Fig.1).The main advantages of the present synthetic protocol are eco-friendly catalyst, easy reaction work-up procedure and precedent some new derivative compounds. It is expected that the present methodology will find application in organic synthesis and industrial chemistry.

Keywords:

Aryl-5 , 10-dihydro-4H-benzo[g]chromene , L-proline , Naphthoquinone