Catalyst-free synthesis of octahydroacridines using glycerol as recyclable solvent

We describe herein the use of glycerol as an efficient, safe and recyclable solvent in the one-pot hetero-Diels-Alder (HDA) reaction of (R)-citronellal with substituted arylamines. The catalyst-free reactions proceed easily using glycerol at 90 °C and the corresponding octahydroacridines (OHAs) were obtained in good to excellent yields by simply decantation of products. After removing the products, glycerol was directly reused for further HDA reactions without lost of activity.