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

• Published in: Organic & biomolecular chemistry Vol. 21; no. 17; pp. 3615 - 3622
• Main Authors: Kirillov, Andrey S, Semenov, Egor A, Bityukov, Oleg V, Kuznetsova, Maria A, Demidova, Valentina N, Rogozhin, Alexander N, Glinushkin, Alexei P, Vil', Vera A, Terent'ev, Alexander O
• Format: Journal Article
• Language: English
• Published: CAMBRIDGE Royal Soc Chemistry 03.05.2023; Royal Society of Chemistry
• Subjects: Ammonium; Anions; Anodizing; Antifungal activity; Carbonyl compounds; Chemistry; Chemistry, Organic; Electrochemistry; Electrolysis; Electrolytes; Functional groups; Fungicides; Halogens; Intermediates; Organic chemistry; Organic compounds; Organic solvents; Oxidants; Oxidation; Oxidizing agents; Physical Sciences; Reagents; Science & Technology; Solvents; Thiocyanates; MILD; KETONES; ONE-POT SYNTHESIS; ELECTROCHEMICAL THIOCYANATION; DIRECT ALPHA-THIOCYANATION; OXIDANT; CARBONYL; CATALYST; SUPPORTED REAGENTS SYSTEM; EFFICIENT REAGENT
• ISSN: 1477-0520; 1477-0539; 1477-0539
• DOI: 10.1039/d3ob00474k

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. The electrochemical synthesis of fungicidal thiocyanates from 1,3-dicarbonyl compounds and ammonium thiocyanate was developed. The high efficiency of electrochemical thiocyanation was only achieved using AcOH as the solvent.