Electrochemically driven green synthesis to unlock sustainable routes to β-keto spirolactones

• Published in: Green chemistry : an international journal and green chemistry resource : GC 2024-06, Vol.26 (11), p.6553-6558
• Main Authors: MacLean, Ian, García, Montaña J, Cabrera, Silvia, Marzo, Leyre, Alemán, José
• Format: Article
• Language: English
• Subjects: Continuous flow; Electrochemistry; Esters; Oxidants; Oxidizing agents; Solvents; Synthesis
• ISSN: 1463-9262; 1463-9270
• DOI: 10.1039/d4gc01127a

In this work, we present a sustainable and environmentally benign electrochemical method for the synthesis of β-keto spirolactones. The reaction is carried out using green solvents such as acetone and water, and simple electrons as oxidants, instead of the stoichiometric oxidants used in classical approaches. The robustness of the method allows the functionalization of cyclic β-keto esters and a β-keto amide, the latter affording α-spiroiminolactone. The method also gives good results with double bonds bearing substituents of different electronic natures. Furthermore, this methodology can be easily scalable through a continuous flow electrochemical approach that improves the productivity of the reaction. Mechanistic investigations support the radicalic nature of the transformation, and the generation of a carbocation intermediate that is further trapped with the water employed as co-solvent in the reaction. A sustainable method efficiently synthesizes β-keto spirolactones using green solvents under electrochemical conditions.