Based on the above problems, there is need to develop a general procedure where it is compatible for alkyne group and Polyethylene group along with to avoid use of column chromatography purification. A range of methods are reported for cyclic dehydration, out of that para toluene sulfonic acid in toluene reflux under condition is more suitable so that by acid base pH manipulation we can avoid the column chromatography purification. So, we applied this method for synthesize the maleimide derivatives ((Method-C). We took bismaleimicacid 3a in toluene under reflux condition in presence of PTSA gives the essentially pure product but in low yield. We understood that solubility of acid bearing substrate in toluene influence the outcome (yields) of the reaction. The maleimide derivatives yields are decreasing when ether linkage is increasing in the bismaleimide because of polarity. To avoid the solubility problem of maleimide acid, we carried out one pot reaction, where the acid is first is converted into ester in methanol in presence of PTSA at room temperature. After concentration*, the crude ester in toluene under reflux condition gives required products without any column chromatography purification in good to excellent yields. (METHOD-D).