Chemical‐Switching Strategy for Synthesis and Controlled Release of Norcantharimides from a Biomass‐Derived Chemical

Abstract

Catalytic strategies were developed to synthesize and release chemicals for applications in fine chemicals, such as drugs and polymers, from a biomass-derived chemical, 5-hydroxymethyl furfural (HMF). The combination of the diene and aldehyde functionalities in HMF enabled catalytic production of acetalized HMF derivatives with diol or epoxy reactants to allow reversible synthesis of norcantharimide derivatives upon Diels-Alder reaction with maleimides. Reverse-conversion of the acetal group to an aldehyde yielded mismatches of the molecular orbitals in norcantharimides to trigger retro Diels-Alder reaction at ambient temperatures and released reactants from the coupled molecules under acidic conditions. These strategies provide for the facile synthesis and controlled release of highvalue chemicals.

The Interplay between Kinetics and Thermodynamics in Furan Diels–Alder Chemistry for Sustainable Chemicals Production

“…Stabilization of 5-HMF/maleimide adducts by acetalization;upon hydrolysis, the formyl adducts undergo cycloreversion. [116] Angewandte Chemie furan and the 2-methylated derivative show the same equilibrium conversion, as demonstrated in ac ompetition experiment. [63] On the other hand, with fumaronitrile,t he equilibrium constants for as eries of 2,5-disubstituted furans follows the trend:M e> Et > Bu > Hex > H, evidently balancing both effects.…”

Advances in Diels–Alder/aromatization of biomass furan derivatives towards renewable aromatic hydrocarbons

“…111,112 In another report, norcantharimide derivatives were synthesized by DA cycloaddition of maleimide and a cyclic acetal prepared from HMF (Scheme 7C). 113 Interestingly, at pH ≤3, acetal bond hydrolysis triggered a molecular orbital mismatch in the DA cycloadducts and induced the retro-DA reaction to readily release the HMF aldehyde and the corresponding dienophile at a constant temperature. Furthermore, the six-membered cyclic acetal product had the highest stability, indicating that it could give the highest yield of DA cycloadducts and lower DA chemical release rate.…”

Recent Advances on Diels‐Alder‐Driven Preparation of Bio‐Based Aromatics

“…Preparation of cyclic acetals from furfurals were also reported to undergo DA with highly electrophilic dienophiles such as maleimides (50 °C, 72 h) [14a] and acrylonitrile (60 °C, 120 h; Scheme 4 A,B). [ 19 , 20 ] Interestingly, when subjected to an acidic trigger (pH<3) the resulting acetal hydrolysis triggers a molecular orbital mismatch in the HMF‐7‐ONB product and induces the retro‐DA reaction to readily release the furfuryl aldehyde and the corresponding dienophile (Scheme 4 B).…”