The yields are much better than from the acid directly. Under these condition Alkyl linked maleimide 4a-4c were isolated in pure form and 4c was characterized by single crystal data (hard copy only). PEG-Maleimide 4d and N-Propargyl maleimide 4e gives good yields whereas as substrate 3f, 3g remain unsuccessful because of free hydroxyl group, which is interfering the reaction, and giving polymeric product. In conclusion, we have established a operationally simple one pot cyclization method for synthesis of pure maleimide derivatives without any column chromatography purification by using PTSA in presence of methanol and toluene under reflux conditions (method-D). The notable advantage of this methodology are simple conditions, industrially applicable, tolerance to a wide range of functionalities.