Figure : Previous conventional sulfation methods including sulfuric acid/sulfamic acid, chlorosulfonic acid, sulfur trioxide amine complexes, and the protection/deprotection methods which suffer from some issues such as multiple-purification steps reactions, toxicity issues (eg pyridine contamination), purification challenges, stoichiometric excess of reagents which leads to increase of a reaction cost, and intrinsic stability issues of both the reagent and product.