Microfluidics Biocatalysis System Applied for the Synthesis of N-Substituted Benzimidazole Derivatives by Aza-Michael Addition

Benzimidazole scaffolds became an attractive subject due to their broad spectrum of pharmacological activities. In this work, a methodology was developed for the synthesis of N-substituted benzimidazole derivatives from benzimidazoles and α, β-unsaturated compounds (acrylonitriles, acrylate esters, phenyl vinyl sulfone) catalyzed by lipase TL IM from Thermomyces lanuginosus in continuous-flow microreactors. Investigations were conducted on reaction parameters such as solvent, substrate ratio, reaction temperature, reactant donor/acceptor structures, and reaction time. The transformation is promoted by inexpensive and readily available lipase in methanol at 45 °C for 35 min. A wide range of β-amino sulfone, β-amino nitrile, and β-amino carbonyl compounds were efficiently and selectively synthesized in high yields (76–97%). All in all, a microfluidic biocatalysis system was applied to the synthesis of N-substituted benzimidazole derivatives, and could serve as a promising fast synthesis strategy for further research to develop novel and highly potent active drugs.

Highly Efficient and Practical N-Heterocyclic Carbene Organocatalyzed Chemoselective N1/C3-Functionalization of Isatins with Green Chemistry Principles

Ecofriendly N-heterocyclic carbene (NHC) organocatalysis can control the N₁-functionalization (aza-Michael addition) and C₃-functionalization (Morita-Baylis-Hillman reaction, MBH) of isatins in the absence of (1) a protecting group, (2) a stoichiometric reagent, and (3) heat energy. The challengeable N₁-functionalization of N-unsubstituted isatins into N-substituted (NS) isatins was realized through 10 mol % NHC and 10 mol % 1,8-diazabicyclo[5.4.0]undec-7-ene catalysts within 10 min with up to 98% isolation yield. The subsequent MBH adducts of as-synthesized NS-isatins (N₁/C₃-functionalization) was perfectly acquired in 10 mol % NHC and 10 mol % 1,4-diazabicyclo[2.2.2]octane catalysis within 30 min with superiority to C₃/N₁-functionalization (MBH/aza-Michael). For guiding the application to a versatile druggable isatin library, the NHC catalysis was compared with reported functionalization of isatins in view of green chemistry principles including solvent scoring of ACS GCI pharmaceutical roundtable, E-factor, atom economy, and so on.

Continuous flow chemistry: where are we now? Recent applications, challenges and limitations

A general outlook of the changing face of chemical synthesis is provided in this article through recent applications of continuous flow processing in both industry and academia. The benefits, major challenges and limitations associated with the use of this mode of processing are also given due attention as an attempt to put into perspective the current position of continuous flow processing, either as an alternative or potential combinatory technology for batch processing.

Enzymatic synthesis of nucleoside analogues from uridines and vinyl esters in a continuous-flow microreactor

We achieved the effective controllable regioselective acylation of the primary hydroxyl group of uridine derivatives catalyzed by Lipase TL IM from Thermomyces lanuginosus with excellent conversion and regioselectivity. Various reaction parameters were studied. These regioselective acylations performed in continuous flow microreactors are a proof-of-concept opening the use of enzymatic microreactors in uridine derivative biotransformations.

We achieved the effective controllable regioselective acylation of the primary hydroxyl group of uridine derivatives catalyzed by Lipase TL IM from Thermomyces lanuginosus with excellent conversion and regioselectivity.