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A new type of biobased acrylates has been synthesized by a Baylis-Hillman reaction of alkylacrylates with aD -glucosyloxymethyl-furfural (a-GMF), available in one step from isomaltulose. The reaction, performed in aqueous medium, was extended to other a,b-unsaturated substrates. The use of dimethylisosorbide as co-solvent was investigated.

Deep eutectic solvents (DESs) are commonly employed as environmentally-friendly solvents in numerous chemical applications owing to their unique physicochemical properties. In this study, a novel and environmentally-friendly extraction method based on ultrasound assisted-deep eutectic solvent extraction (UAE-DES) was investigated for the extraction of flavonoids from Cyclocarya paliurus (Batal.) Iljinskaja (C. paliurus) leaves, and the antioxidant activities of these flavonoids were evaluated. Nine different DES systems based on either two or three components were tested, and the choline chloride/1,4–butanediol system (1:5 molar ratio) was selected as the optimal system for maximizing the flavonoid extraction yields. Other extraction conditions required to achieve the maximum flavonoid extraction yields from the leaves of C. paliurus were as follows: DES water content (v/v), 30%; extraction time, 30 min; temperature, 60 °C; and solid-liquid ratio, 20 mg/mL. Liquid chromatography-mass spectrometry allowed the detection of five flavonoids in the extract, namely kaempferol-7-O-α-l-rhamnoside, kaempferol, quercetin, quercetin-3-O-β-d-glucuronide, and kaempferol-3-O-β-d-glucuronide. In vitro antioxidant tests revealed that the flavonoid-containing extract exhibited strong DPPH and ABTS radical-scavenging abilities. Results indicate that UAE-DES is a suitable approach for the selective extraction of flavonoids from C. paliurus leaves, and DESs can be employed as sustainable extraction media for other bioactive compounds.

The Baylis-Hillman reaction of HMF was investigated in various biobased solvent systems and in water. 10 Although pure water is able to promote the reaction, aqueous mixtures with ethanol, isopropanol, methyl-THF (MeTHF), tetrahydrofurfuryl-alcohol (THFA) show better overall efficacy for HMF Baylis-Hillman reaction than pure water or pure bio-based solvent. Such solvent systems can replace THF or dioxane, often used for BH reactions. Pure biobased solvents can be however used in the case of the more polar glucosyloxymethylfurfural (GMF). These results show that the most appropriate medium must also take 15 into account the polarity of the starting aldehyde.

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