A novel, green and efficient visible-light-promoted decarboxylative aminoalkylation reaction of imidazo[1,2-a]pyridines with N-aryl glycines has been described.
PPL, lipase from porcine pancreas, is first reported to catalyze direct asymmetric aldol reactions between aromatic aldehydes and cyclic ketones. More importantly, the catalytic activity of PPL was greatly promoted by a small quantity of water at 37 °C. A wide range of aromatic aldehydes reacted with cyclic ketones to provide the corresponding aldol products with high yields (up to 99 %) and moderate to good stereoselectivity (up to 90 % ee and 99:1 dr).
A mild and efficient method catalyzed by α-chymotrypsin was developed for the synthesis of bis(indolyl)methanes through a cascade process between indole and aromatic aldehydes. In the ethanol aqueous solution, a green medium, a wide range of aromatic aldehydes could react with indole to afford the desired products with moderate to good yields (from 68% to 95%) using a little α-chymotrypsin as catalyst.
Background
Production of biodiesel from renewable sources such as inedible vegetable oils by enzymatic catalysis has been a hotspot but remains a challenge on the efficient use of an enzyme. COFs (Covalent Organic Frameworks) with large surface area and porosity can be applied as ideal support to avoid aggregation of lipase and methanol. However, the naturally low density limits its application. In this work, we reported a facile synthesis of core–shell magnetic COF composite (Fe3O4@COF-OMe) to immobilize RML (Rhizomucor miehei lipase), to achieve its utilization in biodiesel production.
Result
This strategy gives extrinsic magnetic property, and the magnetic COFs is much heavier and could disperse in water medium well, facilitating the attachment with the enzyme. The resultant biocomposite exhibited an excellent capacity of RML due to its high surface area and fast response to the external magnetic field, as well as good chemical stability. The core–shell magnetic COF-OMe structure not only achieved highly efficient immobilization and recovery processes but also maintained the activity of lipase to a great extent. RML@Fe3O4@COF-OMe performed well in practical applications, while free lipase did not. The biocomposite successfully achieved the production of biodiesel from Jatropha curcas Oil with a yield of about 70% in the optimized conditions.
Conclusion
Magnetic COFs (Fe3O4@COF-OMe) for RML immobilization greatly improved catalytic performance in template reaction and biodiesel preparation. The magneticity makes it easily recovered and separated from the system. This first successful attempt of COFs-based immobilized enzyme broadened the prospect of biodiesel production by COFs with some inspiration.
Herein, we reported a practical and efficient strategy combining
photoredox and enzyme catalysis for the construction of 3-aminoalkyl
chromones from o-hydroxyaryl enaminones and N-arylglycine esters. A variety of 3-aminoalkyl chromones
were synthesized with good yields under mild conditions in one pot.
This synthetic protocol consists of sequential enzymatic hydrolysis
and photoredox decarboxylation of N-arylglycine esters,
oxidation of aminoalkyl radicals, Mannich reaction, and intramolecular
nucleophilic cyclization, which affords a convenient pathway for the
preparation of various 3-substituted chromones.
We report a simple oxidative Csp 3 À H functionalization reaction of glycine derivatives by visible-light photoredox catalysis. A wide range of glycine derivatives readily undergo the oxidative cyclization to afford various 2-substituted benzoxazoles. Importantly, this photocatalytic intramolecular dehydrogenative coupling reaction allows for the CÀ H functionalization of glycine derivatives involving short peptides under mild conditions, which may have value in preparing peptide-derived pharmacologically active molecules.
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