One-pot three-component synthesis of 3,4-dihydro-3,3-dimethyl-9-phenylacridin-1(2H,9H,10H)-one derivatives has been described by the cyclocondensation of aromatic aldehydes, aromatic amines and dimedone in the presence of 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) in ethanol at reflux condition. Besides buffering agent, HEPES as an organocatalyst has been used for the first time in multicomponent organic transformation and succeeded along with various merits of green chemistry practices. The reaction is mechanized by zwitterionic interactions between organocatalyst and reactants to form targeted molecules.