Memory of Chirality in Room Temperature Flow Electrochemical Reactor

Abstract

<p>Many chiral compounds have become of great interest to the pharmaceutical industry as they possess various biological activities. Concurrently, the concept of “memory of chirality” has been proven as a powerful tool in asymmetric synthesis, while flow chemistry has begun its rise as a new enabling technology to add to the ever increasing arsenal of techniques available to the modern day chemist. Here, we have employed a new simple electrochemical microreactor design to oxidise an L-proline derivative at room temperature in continuous flow. Electrochemical methods are inherently green and environmentally benign. However, organic electrosynthesis via microflow reactor has number of advantages such as fast reaction’s time, optimization and scale up, safer environment, high selectivities and reduce chances of overoxidation. Flow electrochemical reactor provides high surface-to-volume ratio and reactions are possible to perform in the reactor without a supporting electrolyte due to a very short interelectrode distance. By the comparison of Hofer Moest type electrochemical oxidations at room temperature in batch and flow, we have achieved that continuous flow electrolysis is better than batch electrolysis, producing a good yield (71%) and a better enantiomeric excess (64%). These results show that continuous flow electrolysis has the potential to act as a new enabling technology for asymmetric synthesis to replace some aspects of conventional batch electrochemical processes. </p>