An environmentally benign way to synthesize 2-thiocyano-1,3-dicarbonyl compounds with high antifungal activity: a key role of solvent

The introduction of thiocyano groups into organic molecules is important for the preparation of many active ingredients and synthetic intermediates. A commonly used and attractive strategy is the nucleophilic substitution of halogens with the SCN anion or oxidative thiocyanation using an excess amount of external oxidants. A sustainable alternative to stoichiometric reagents is electrochemistry based on anodic oxidation of the SCN anion and other intermediates. Electrochemical thiocyanation of various organic compounds, carried out in the usual non-acidic organic solvents, is well known. Here, we present an electrochemical thiocyanation of 1,3-dicarbonyl compounds in which high efficiency was only achieved using AcOH as the solvent. Electrolysis proceeds in an undivided cell under constant current conditions without any additional halogen-containing electrolytes. Ammonium thiocyanate was used as the source of the SCN group and the electrolyte. Electrochemical thiocyanation of 1,3-dicarbonyl compounds begins with the generation of (SCN)(2) from the thiocyanate anion, followed by the addition of thiocyanogen to the double bond of the enol tautomer of 1,3-dicarbonyl compounds, which finally gives the products. A variety of thiocyanated 1,3-dicarbonyl compounds bearing different functional groups were obtained in 37-82% yields and were shown to exhibit high antifungal activity.

Automated summary

The introduction of thiocyano groups into organic molecules is crucial for the synthesis of active ingredients and synthetic intermediates. Electrochemical thiocyanation provides a sustainable alternative to traditional methods, with high efficiency observed in the electrochemical thiocyanation of 1,3-dicarbonyl compounds using AcOH as the solvent. The resulting thiocyanated compounds exhibited high antifungal activity.