Synthesis of Novel Cinnamoyl Amides Using a Solvent-Free Microwave-Assisted Method

Abstract

A novel series of potential biologically active new cinnamoyl amides were synthesized in good yield and short reaction times. We have studied the one-pot, solvent-free reaction of cinnamic acid derivatives with aromatic amines using 1,3-dicyclohexylcarbodiimide under microwave irradiation in the presence of small quantities of dimethylformamide to improve energy transfer.

GRAPHICAL ABSTRACT

Keywords:

• Cinnamoyl amides
• condensation
• microwave heating
• solvent-free reaction
• synthetic methods

ACKNOWLEDGMENTS

The authors thank Antonio Marchal Igrain and Juan Jesús López González from University of Jaén, Spain, for their kindness for measuring NMR spectra.

Notes

^a MW conditions: P = 180 W, reaction time: 10 min.

^b Cinnamic acid–amine–DCC.

^c Isolated yields.

^a Reaction conditions: cinnamic acid (20 mmol), amine (20 mmol), DCC (20 mmol), DMF (3 drops), 120 W.

^b Method MW: The temperature was controlled throughout the reaction and evaluated by infrared detector, which indicated the surface temperature after calibration with an optical fibre.

^c Method Δ: The temperature was controlled using a digital thermometer inside the reaction mixture.

^d Yields (%) refer to those of pure isolated products properly characterized by spectroscopic data (¹H, ¹³C NMR, MS).