Recent Advances in Asymmetric Catalysis in Flow

Abstract

Asymmetric catalysis in flow has been attracting much attention very recently because of the potential advantages over its batchwise counterpart, such as high-throughput screening and synthesis, easy automation with the integration of on-demand reaction analysis, little or no reaction workup, and potential long-term use of the catalysts in the case of heterogeneous catalysis. Homogeneous asymmetric catalysis performed in a microreactor has demonstrated successful examples in fast catalyst screening, integrated inline/onlineanalysis, microflow photocatalysis, multistep transformation with unstable intermediates, and potential for lower catalyst loading or homogeneous catalyst recylcing. Since heterogeneous asymmetric catalysis serves as a better way than its homogeneous analogue for catalyst separation and recycling, this Review Article summarizes recent development via different catalyst immobilization methods, such as covalent support, a self-supported method, an adsorption method, and H-bonding, electrostatic or ionic interaction, and nonconventional media, as well. In addition, biocatalysis, including enzyme-catalyzed kinetic resolution and transformation, in flow will be discussed either in homogeneous or heterogeneous mode.

Ferrocene-derived P,N ligands: synthesis and application in enantioselective catalysis

“…We believe that these ligands should be part of each chiral ligand kit for the initial screening of ligands for any new enantioselective reaction. Recently, continuous-flow microreactors have received a significant amount of interest to facilitate rapid screening of chiral catalysts [104,105].…”

A Microfluidic Toolbox for the Development of In-Situ Product Removal Strategies in Biocatalysis

“…There are numerous benefits and key features associated with the application of microfluidic modules [37,45,92,[94][95][96][97][98]. Some of these benefits and features are essential for the development and testing of ISPR/IScPR process concepts in an easy, fast and reliable manner (Fact box 2).…”

“…Implementation of on-line and/or in-line monitoring will furthermore make it possible to operate the microfluidic modules fully automatic [92], i.e., no/minimal manual sample handling is required during experiments. This will ultimately result in high throughput testing and improved reproducibility along with developing detailed knowledge of the tested process concepts [94]. The large surface-to-volume ratio and small characteristic length scales in microfluidic channels enable fast mass transfer, which is important for ISPR/IScPR applications [20].…”

Asymmetric one-pot reactions using heterogeneous chemical catalysis: recent steps towards sustainable processes

“…However, oftentimes by appropriate material design, robust and stable chiral catalysts have been obtained, which allow preserved performances upon recycling, and the possibility of application in flow systems. [32][33][34] Further increase in the sustainability of the catalytic reactions may result from carrying out several reactions in a single vessel, without isolation of the intermediate products in a so-called one-pot procedure. [35][36][37][38] One-pot reactions that allow two or more bond-forming transformations under the same conditions without intervention and with subsequent transformations occurring at the functionalities resulting from a previous step, are designated domino or cascade reactions.…”