Renewable Thiophene Synthesis from Biomass Derived Methyl Levulinate and Elemental Sulfur

Heterocyclic compounds are pivotal building blocks in petrochemical and renewable fine chemical synthesis. The production of bio-based heterocyclic compounds is limited to furans and pyrroles, while thiophenes are rarely prepared from bio-based feedstock in a real renewable method. Current research on the "pseudo-renewable" thiophene synthesis strongly relies on unwieldy Lawesson's Reagent, which makes the process unsustainable. The present work describes for the first time that, two thiophene diesters were synthesized from biomass-derived methyl levulinate and elemental sulfur, a cheap, surplus by-product of the fossil industry that is causing potential pollution. The condensation and sulfurization steps in this process all involved multiple reaction pathways, leading to a much more intricate mechanism than previous research in its type. The footprint of sulfur in this system was tracked throughout the process, and the chemistry of this multi-step reaction provided a new orientation for the real sustainable thiophene synthesis based on elemental sulfur.