The one-pot diastereoselective synthesis of new <i>N</i>-substituted octahydroacridines was successfully achieved via BiCl₃-catalyzed intramolecular cationic imino Diels–Alder reaction in good yields employing <i>N</i>-protected anilines and (±)-citronellal as substrates under mild conditions. It was observed that bulky <i>N</i>-substituent groups (allyl, propargyl, and benzyl substituent) play a key role in the <i>cis</i>/<i>trans</i> ratio of the thus-formed octahydroacridines. Increasing bulkiness permits preferential formation of the <i>trans</i>-fused heterocycles. It was found that use of the <i>N</i>-benzyl group resulted in a highly diastereoselective process that gives easily separable <i>trans</i>-fused <i>N</i>-substituted octahydroacridines. The developed protocol was extended to involve the use of citronella essential oil from <i>Cymbopogon nardus</i> as a renewable source of these biologically important heterocyclic molecules.