Electrocatalytic synthesis of heterocycles from biomass-derived furfuryl alcohols

Abstract

It is very attractive yet underexplored to synthesize heterocyclic moieties pertaining to biologically active molecules from biomass-based starting compounds. Herein, we report an electrocatalytic Achmatowicz reaction for the synthesis of hydropyranones from furfuryl alcohols, which can be readily produced from biomass-derived and industrially available furfural. Taking advantage of photo-induced polymerization of a bipyridyl ligand, we demonstrate the facile preparation of a heterogenized nickel electrocatalyst, which effectively drives the Achmatowicz reaction electrochemically. A suite of characterization techniques and density functional theory computations were performed to aid the understanding of the reaction mechanism. It is rationalized that the unsaturated coordination sphere of nickel sites in our electrocatalyst plays an important role at low applied potential, not only allowing the intimate interaction between the nickel center and furfuryl alcohol but also enabling the transfer of hydroxide from nickel to the bound furfuryl alcohol.

Unraveling the Mechanisms of Electrocatalytic Oxygenation and Dehydrogenation of Organic Molecules to Value‐Added Chemicals Over a Ni–Fe Oxide Catalyst

“…Having demonstrated, guided by the mechanistic study, that the electrocatalyst can be used as a common platform for the electro‐oxidative oxygenation and dehydrogenation of aliphatic and benzylic alcohols and benzylamine, [ 45 ] we then extended this scope to a more complex reaction, the highly important six‐electron selective oxidation of 5‐(hydroxymethyl)furfural (HMF) to 2,5‐furandicarboxylic acid (FDCA), an essential platform chemical in the polymer industry, ( Figure 7 a). [ 46–49 ] The 1 H NMR peak at ≈4.5 ppm, measured in the starting material, is ascribed to the hydroxymethyl H (H d ). It completely vanishes in the postreaction mixture (Figure 7b, blue), suggesting full conversion of the starting HMF.…”

Low-temperature water electrolysis: fundamentals, progress, and new strategies

“…This hybrid water electrolysis demonstrates great potential for H 2 production and electrochemical organic reforming. [312][313][314] Normally, this hybrid water electrolysis technology produces H 2 at the cathode and nongaseous oxidative products. Very recently, Wang et al reported a novel hybrid water electrolyser that combines the cathodic HER and low-potential anodic oxidation of aldehyde with a low onset voltage of merely 0.1 V. 315 Unlike conventional aldehyde electrooxidation at the anode, in which the hydrogen atom of the aldehyde group is oxidized into H 2 O at high potentials and nongaseous product molecules are generated, the lowpotential aldehyde oxidation can produce H 2 from the hydrogen atom of aldehyde at the anode.…”

The Renaissance of Electro‐Organic Synthesis for the Difunctionalization of Alkenes and Alkynes: A Sustainable Approach

“…This problem could be overcomed by employing modified electrodes fabricated with the catalyst which could be highly advantageous in synthesizing a variety of organic molecules. [130][131][132][133][134] These modified electrodes have higher surface area which reduces the current density and avoid the degradation of electrolytes. The fabrication of the catalyst to the electrode makes it advantageous for reusability and easier isolations of the desired product.…”

“…Moreover, the catalyst used in the electrochemical transformations are transition metals, ionic salts, organic hydrazines or organic amines and the use of these catalyst in the solution brings along major disadvantages including difficult isolation and unavoidable side products. This problem could be overcomed by employing modified electrodes fabricated with the catalyst which could be highly advantageous in synthesizing a variety of organic molecules [130–134] . These modified electrodes have higher surface area which reduces the current density and avoid the degradation of electrolytes.…”