Torii-Type Electrosynthesis of α,β-Unsaturated Esters from Furfurylated Ethylene Glycols and Amino Alcohols

Article abstract of DOI:10.1002/ejoc.202100605

Electrosynthesis of unsaturated esters from furan derivatives, reported by Torii et al. in 1976, is an attractive method for the valorization of furanoic platform chemicals. Nevertheless, it has received practically no attention, presumably due to specific reaction conditions including the use of expensive Pt electrodes. With the aim of expanding the application of Torii-type ester electrosynthesis, we explored the electrochemical transformation of O-furfuryl ethylene glycols and N-furfuryl amino alcohols to esters 5. These can be obtained in two consecutive electrochemical steps: bis-alkoxylation of the furan derived substrates 3 to give spirocycles 4, followed by ring-opening involving oxidative fragmentation of the C?C bond. Both steps can be carried out at ambient conditions, using inexpensive graphite electrodes; however, each step required a different supporting electrolyte and acidic additive to achieve good yields of the product. Additionally, conditions were found for efficient one-pot transformation of N-furfuryl amino alcohols to esters 5 while O-furfuryl ethylene glycols under the same conditions gave esters 5 in moderate yields.