L-Carvone-based intermediate 3 (1.67 g, 6.00 mmol), aryl aldehyde (7.00 mmol), and potassium hydroxide (0.34 g, 6.06 mmol) were mixed and dissolved in anhydrous ethanol (20 mL). The reaction mixture was continuously stirred and refluxed for 6 h. Upon completion of the reaction, the mixture was left to cool, and a vast amount of yellow powder was precipitated. The precipitate was filtered and washed with anhydrous ethanol several times to afford target compounds 4a ~4y as yellow powders with yields of 77.4~91.6%.
Free full text: Click here
