Electroorganic synthesis of 2,5-dialkoxydihydrofurans and pyridazines on solid phase using polymer beads as supports

Electroorganic synthesis has defied application in Solid-Phase Organic Synthesis (SPOS) so far. Typically more than 99.9% of the substrate molecules immobilized on a polymeric support are buried in the interior of the bead, and therefore are unable to undergo direct contact with a heterogeneous reagent such as an electrode. This intrinsic impediment for an electrochemical reaction can be overcome by the use of a redox mediator which shuttles electrons from the electrode to the polymer bound substrate molecules. This approach of indirect electroorganic synthesis was successfully applied for the 2,5-dialkoxylation of furans on solid phase. The oxidation products can be hydrolyzed and through condensation with hydrazine hydrate substituted pyridazines are produced in 50-65% overall yield.