One‐Pot Synthesis of Thiocarbamates. Issue 31 (19th August 2021) - Waibel, Kevin A.
Abstract: An efficient isocyanide‐based synthesis of S ‐thiocarbamates was discovered and thoroughly investigated. The new reaction protocol is a one‐pot procedure and allows the direct conversion of N ‐formamides into thiocarbamates by initial dehydration with p ‐toluene sulfonyl chloride to the respective isocyanide and subsequent addition of a sulfoxide component. Contrary to recent literature, which also uses isocyanides as starting material, but with other sulfur reagents than sulfoxides, in this protocol, no isolation and purification of the isocyanide component is necessary, thus significantly decreasing the environmental impact and increasing the efficiency of the synthesis. The new protocol was applied to synthesize a library of sixteen thiocarbamates, applying four N ‐formamides and four commercially available sulfoxides. Furthermore, experiments were conducted to investigate the reaction mechanism. Finally, four norbornene‐based thiocarbamate monomers were prepared and applied in controlled ring‐opening metathesis polymerization (ROMP) reactions. The polymers were characterized by size‐exclusion chromatography (SEC) and their properties were investigated utilizing differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Abstract : A library of sixteen S ‐thiocarbamates was synthesized utilizing a newly discovered one‐pot synthetic procedure starting from N ‐formamides, which omits isolation of the isocyanide intermediate. Experiments were conducted to investigate the mechanism and identify side‐reactions and side‐products. Finally, four norbornene‐based thiocarbamates were polymerized by ring‐opening metathesis polymerization (ROMP) and characterized thereafter.