A Combined Experimental-Theoretical Study on Diels-Alder Reaction with Bio-Based Furfural: Towards Renewable Aromatics

The synthesis of relevant renewable aromatics from bio-based furfural derivatives and cheap alkenes is carried out by using a Diels-Alder/aromatization sequence. The prediction and the control of theortho/metaselectivity in the Diels-Alder step is an important issue to pave the way to a wide range of renewable aromatics, but it remains a challenging task. A combined experimental-theoretical approach reveals that, as a general trend,orthoandmetacycloadducts are the kinetic and thermodynamic products, respectively. The nature of substituents, both on the dienes and dienophiles, significantly impacts the feasibility of the reaction, through a modulation on the nucleo- and electrophilicity of the reagents, as well as theortho/metaratio. We show that theortho/metaselectivity at the reaction equilibrium stems from a subtle interplay between charge interactions, favoring theorthoproducts, and steric interactions, favoring themetaisomers. This work also points towards a path to optimize the aromatization step.

Automated summary

In this study, a Diels-Alder/aromatization sequence is used to synthesize renewable aromatics from bio-based furfural derivatives and inexpensive alkenes. The control of ortho/meta selectivity in the Diels-Alder step is crucial for developing a wide range of renewable aromatics. Experimental and theoretical approaches show that ortho and meta cycloadducts are kinetic and thermodynamic products, respectively, and the feasibility of the reaction is significantly impacted by substituents on the reactants.