Search

Using Novozyme N435 in organic media led to selective deacetylation of various pyranose saccharides. Two of the products were then used to synthesise 6'-galactosyllactose in overall a short pathway.

An expansion of the solvent-free synthetic toolbox is essential for advances in the sustainable chemical industry. Mechanochemical reactions offer a superior safety profile and reduced amount of waste compared to conventional solvent-based synthesis. Herein we report a new mechanochemical method for nucleophilic substitution of alcohols using fluoro-N,N,N′,N′-tetramethylformamidinium hexafluorophosphate (TFFH) and K2HPO4 as an alcohol-activating reagent and a base, respectively. Alcohol activation and reaction with a nucleophile were performed in one milling jar via reactive isouronium intermediates. Nucleophilic substitution with amines afforded alkylated amines in 40–91% yields. The complete stereoinversion occurred for the SN2 reaction of (R)- and (S)-ethyl lactates. Substitution with halide anions (F−, Br−, I−) and oxygen-centered (CH3OH, PhO−) nucleophiles was also tested. Application of the method to the synthesis of active pharmaceutical ingredients (APIs) has been demonstrated.

We found that cyclohexanohemicucurbit[8]uril encapsulates five- and six-membered sulfur- and oxygen-containing unsubstituted heterocycles and can be used as a selective sorption material for the extraction of sulfur-heterocycles like 1,3-dithiolane and α‑lipoic acid from water.

Here we report a study on cyclohexanohemicucurbit[8]uril (cycHC[8]) binding of sulfur-, oxygen- and nitrogen-containing heterocycles in both solid state and solution, which is investigated by single crystal X-ray diffraction, NMR spectroscopy, isothermal titration calorimetry, and thermogravimetry. Potential guests include environmental pollutants, hazardous compounds, and bioactive substances. We found that cycHC[8] encapsulates five- and six-membered sulfur- and oxygen-containing unsubstituted heterocycles and can be used as a selective sorption material for the extraction of sulfur-heterocycles from water. Both cycHC[6] and cycHC[8] can remove a substituted heterocycle, α-lipoic acid, from an aqueous solution via the formation of an external complex. The results show that cycHC[n] is a promising reusable sorbent material with the potential to be employed in molecular recognition and highly specific solid-phase extraction of sulfur-heterocycles.

Conversion of biobased platform chemicals to enantiopure compounds has become topical. We report a straightforward synthesis of 4-(acyloxy)-pentanoic acids from gamma-valerolactone (GVL). An alkaline hydrolysis of GVL is followed by a stereoselective lipase-catalyzed acylation of the sodium salt. Acidic hydrolysis of the acylation product affords (R)-4-(acyloxy)-pentanoic acid and relactonized (S)-GVL. (R)-4-(Propionyloxy)-pentanoic acid and (R)-GVL are obtained with e.r. > 99/1. An additional enzymatic step following a slightly modified process affords (S)-4-(acetyloxy)pentanoic acid with e.r. > 99/1. Simple access to enantiopure 4-(acyloxy)pentanoic acids will stimulate the development of their novel applications, including biobased isotactic polymers.

Solid-state reactions using mechanochemical activation have emerged as solvent-free atom-efficient strategies for sustainable chemistry. Herein we report a new mechanochemical approach for the amide coupling of carboxylic acids and amines, mediated by combination of (1-сyano-2-ethoxy-2-oxoethylidenaminooxy)dimethylaminomorpholinocarbenium hexafluorophosphate (COMU) or N,N,N′,N′-tetramethylchloroformamidinium hexafluorophosphate (TCFH) and K2HPO4. The method delivers a range of amides in high 70–96% yields and fast reaction rates. The reaction protocol is mild, maintains the integrity of the adjacent to carbonyl stereocenters, and streamlines isolation procedure for solid amide products. Minimal waste is generated due to the absence of bulk solvent. We show that K2HPO4 plays a dual role, acting as a base and a precursor of reactive acyl phosphate species. Amide bonds from hindered carboxylic acids and low-nucleophilic amines can be assembled within 90 min by using TCFH in combination with K2HPO4 or N-methylimidazole. The developed mechanochemical liquid-assisted amidation protocols were successfully applied to the challenging couplings of all six carboxylate functions of biotin[6]uril macrocycle with phenylalanine methyl ester, resulting in an 80% yield of highly pure hexa-amide-biotin[6]uril. In addition, fast and high-yielding synthesis of peptides and versatile amide compounds can be performed in a safe and environmentally benign manner, as verified by green metrics.

Seabuckthorn pomace (SBT-P) valorization is gaining importance due to the presence of health promoting bioactive compounds. Designed with a green refinery approach, carotenoids (a bioactive pigment) was extracted from SBT-P using green extraction technologies (Ultrasound- and Microwave-assisted extraction, UAE & MAE), synergized with corn and olive oils used as green solvents. Total carotenoid content (TCC) in SBT-P extracts ranged between 26.91 ± 1.96 and 34.35 ± 0.94 mg/100 g in UAE & MAE. Among the different extraction techniques, HPLC data revealed UAE and olive oil extracts to exhibit highest yield of major carotenoids ( lycopene 87.0; β--carotene 18.7 mg/L). The percent inhibition of DPPH free radical ranged between 92.49 ± 1.84 and 94.16 ± 1.06%, whereas total phenolic content ranged from 341.02 ± 10.97 to 405.58 ± 9.58 mg gallic acid equivalent (GAE)/g of extract in UAE and MAE, respectively. Results encourages the use of green technologies for extraction of bioactive carotenoids from SBT-P and are expected to find potential food industrial applications, where natural pigments are in demand.

A simple and selective C-alkylation of 1- and 2-naphthols with benzylic and allylic halides was developed. In an organic solvent, like cyclopentyl methyl ether, or toluene in the presence of the ether or alcohol additives, a selective ortho-addition leading to substituted naphthalenones up to 90 % was achieved.

Solvent-free, atom-efficient, and mechanochemically activated reactions have emerged as synthetic strategy for sustainable chemistry. Herein we report a new mechanochemical approach for the amide c...

Solid-phase extraction that utilizes selective macrocyclic receptors can serve as a useful tool for removal of chemical wastes. Hemicucurbiturils are known to form inclusion complexes with suitably sized anions; however, their use in selective binding of non-charged species is still very limited. In this study, we found that cyclohexanohemicucurbit[8]uril encapsulates five- and six-membered sulfur- and oxygen-containing unsubstituted heterocycles, which is investigated by single-crystal X-ray diffraction, NMR spectroscopy, isothermal titration calorimetry, and thermogravimetry. The macrocycle acts as a promising selective sorption material for the extraction of sulfur heterocycles, such as 1,3-dithiolane and α-lipoic acid, from water.