Electrocatalytic [3 + 2] Annulation for the Synthesis of Polysubstituted Furans

Abstract

In this report we describe an atom-economic, practical strategy for the synthesis of tri/tetra-substituted furans through electrochemical [3 + 2] annulation between alkynes and β-keto compounds with ferrocene (Fc) as the catalyst. This protocol features the use of a graphite felt (GF) anode and a stainless steel (SST) cathode, mild conditions, and excellent tolerance with various alkynes and β-keto compounds. Additionally, the application of this method is highlighted by the late-stage functionalization of complex structures and a gram-scale experiment.

Ferrocene as a Redox Catalyst for Organic Electrosynthesis

“…[78] Chen, Li, and Zhao and their team found that 1,3-dicarbonyl compounds 51, which lacked a properly positioned aryl group, underwent annulation with alkynes, leading to the production of densely functionalized furans 53 (Figure 11C). [85] These studies further underscore the versatility and efficiency of electrocatalytic methods in the synthesis of complex organic compounds.…”

Synthesis of Polysubstituted Furans: An Update Since 2019

“…[134] In view of this, Chen et al in 2023 described a electro-catalytic synthesis of polysubstituted furans 274 through a tandem [3 + 2] annulation between alkynes 269 and β-keto compounds 270 with ferrocene (Fc) as the catalyst. [135] This technique makes use of a graphite felt (GF) anode and a stainless steel (SST) cathode. Initially, anodic oxidation of Fc formed Fc + species, which on reaction with NaOAc oxidized the β-keto compound to carbon-centered radical 271 and Fc catalyst was regenerated.…”

“…In view of this, Chen et al. in 2023 described a electro‐catalytic synthesis of polysubstituted furans 274 through a tandem [3+2] annulation between alkynes 269 and β ‐keto compounds 270 with ferrocene (Fc) as the catalyst [135] . This technique makes use of a graphite felt (GF) anode and a stainless steel (SST) cathode.…”