To a solution of organic acid (8 mmol, 1.0 equiv.) in EtOH (45mL), 3 drops of concentrated H2SO4 were added and the mixture stirred under reflux for 5 h. The reaction was diluted with saturated aqueous solution of NaHCO3 and extracted 3 times with EtOAc. The combined organic layers were dried over MgSO4, filtered and solvent removed via rotary evaporator.