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Abstract Environmental concern has motivated an inclination to exploit waste and upgrade it into high‐added‐value chemicals. Biomass is an excellent carbon source that provides a variety of raw materials as building blocks, such as furans. Herein, we report the upcycling of furfurol, a known biomass by‐product, through a Diels‐Alder cycloaddition with maleimides that is performed in a green bio‐derived solvent, 2‐MeTHF. We provide two alternative sets of reaction conditions to promote exo or endo selectivity, which depends on the temperature employed. A variety of products were obtained in 70–96 % yield and high exo selectivity at 80 °C, while a 30 : 70‐45 : 55 exo / endo ratio was produced at room temperature. A large‐scale reaction was also performed.
Skolia et al. (Wed,) studied this question.