Chemistry of Outlandish Natural Products Belonging to Sulfur Metabolism: Unrevealed Green Syntheses and Separation Strategies from the Cavallini's Old School

The last century has been very important from the point of view of research and investigation in the fields of the chemistry and biochemistry of sulfur-containing natural products. One of the most important contributions to the discovery and study of human sulfur-containing metabolites was performed by the research group of Professor Doriano Cavallini at Sapienza University of Rome, during the last 80 years. His research brought to light the discovery of unusual sulfur metabolites that were chemically synthesized and determined in different biological specimens. Most of his synthetical strategies were performed in aqueous conditions, which nowadays can be considered totally in line with the recent concepts of the green chemistry. The aim of this paper is to describe and summarize synthetic procedures, and purification and analytical methods from the Cavallini's school, with the purpose to provide efficient and green methodologies for the preparation and obtainment of peculiar unique sulfur-containing metabolites.