Sulfated tungstate in organic synthesis: A review

Sulfated tungstate is a highly efficient, reusable, and environmentally friendly solid acid catalyst used in many organic reactions. Its strong Brönsted acidity, thermal stability, low toxicity, simple preparation, and excellent recyclability make it a good alternative to traditional acid catalysts. In the last twenty years, sulfated tungstate has been used in C–C, C–N, C–O, and C–S bond-forming reactions, multicomponent reactions, heterocycle synthesis, oxidation, and selective protection and deprotection steps. The catalyst works well under mild, solvent-free conditions, affording high yields, a wide range of compatible substrates, and good tolerance to various functional groups. This review covers how sulfated tungstate is prepared, characterized, and used in key organic reactions, such as amidation, transamidation, Ritter, Strecker, Kindler, Willgerodt-Kindler, Biginelli, and cycloaddition reactions. It focuses on reaction mechanisms, catalyst recyclability, synthetic methods, recent progress, current challenges, and future directions, highlighting its importance in sustainable and green organic synthesis.