Cobalt catalyzed electrochemical [4 + 2] annulation for the synthesis of sultams

• Published in: Green chemistry : an international journal and green chemistry resource : GC Vol. 22; no. 5; pp. 1548 - 1552
• Main Authors: Cao, Yangmin, Yuan, Yong, Lin, Yueping, Jiang, Xiaomei, Weng, Yaqing, Wang, Tangwei, Bu, Faxiang, Zeng, Li, Lei, Aiwen
• Format: Journal Article
• Language: English
• Published: CAMBRIDGE Royal Soc Chemistry 09.03.2020; Royal Society of Chemistry
• Subjects: Alkynes; Anodizing; Catalysts; Chemical reactions; Chemistry; Chemistry, Multidisciplinary; Cobalt; Electrochemistry; Green & Sustainable Science & Technology; Green chemistry; Organic chemistry; Oxidants; Oxidation; Oxidizing agents; Physical Sciences; Science & Technology; Science & Technology - Other Topics; Sulfonamides; OXIDATIVE CROSS-COUPLING/CYCLIZATION; REARRANGEMENT; ALKENES; OLEFINATION; PYRROLIDINES; ARYL SULFONAMIDES; 1,1-DIOXIDES; ALKYNES; C-H ACTIVATION; ACCESS
• ISSN: 1463-9262; 1463-9270
• DOI: 10.1039/d0gc00289e

Cobalt catalyzed electrochemical [4 + 2] annulation of sulfonamides with alkynes is demonstrated in this work, which provided a practical and environmentally friendly way to synthesize structurally diverse sultams. Notably, by employing anodic oxidation in an undivided cell to recycle the cobalt catalyst, this electrochemical method avoided the utilization of stoichiometric amount of metallic oxidant, delivering H 2 as the sole by-product. Moreover, this cobalt catalyzed electrochemical protocol proved to be practical and scalable. When the model reaction was scaled up to 5.0 mmol, 86% yield of product could still be obtained. Cobalt catalyzed electrochemical [4 + 2] annulation of sulfonamides with alkynes is demonstrated in this work, which provided a practical and environmentally friendly way to synthesize structurally diverse sultams.