A One-Pot/Single-Analysis Approach to Substrate Scope Investigations Using Comprehensive Two-Dimensional Gas Chromatography (GC×GC)

One-Pot Multisubstrate Screening for Asymmetric Catalysis Enabled by 19F NMR-Based Simultaneous Chiral Analysis

Exploring a diverse chemical space is essential for advancing asymmetric synthesis. The complexity of the chirality-determining processes often requires resource-intensive optimization campaigns across multiple substrates. Although one-pot multisubstrate screening offers a promising solution for high-throughput screening (HTS), a persistent challenge lies in the accurate and efficient analysis of complex reaction mixtures, which has traditionally relied on chromatography-based techniques with limited resolution. In this work, we present a rapid multisubstrate screening workflow that utilizes 19F NMR spectroscopy for simultaneous chiral analysis. By employing an NMR-shifting cobalt reagent, we accurately determined both yields and enantiomeric excesses for up to 21 different substrates in a single reaction mixture during the ruthenium-catalyzed asymmetric reductive amination of ketones. This method facilitates precise chiral analysis through dynamic peak shifts and splitting in 19F NMR spectra induced by the shift reagent. This approach accelerates the evaluation of structure-selectivity relationships, offering valuable mechanistic insights into enantio-determining processes.

Recent Progress on One-Pot Multisubstrate Screening

Traditionally, new synthetic reactions have been developed using a model substrate to screen reaction conditions before testing the optimized conditions with a range of more complex substrates. In 1998, Gao and Kagan pooled multiple substrates in one pot to study the generality of an enantioselective method. Although such one-pot multisubstrate screenings may be powerful, few applications have appeared in the literature. With the advancement of various chromatography techniques, it may be time to revisit this underutilized platform. This review article discusses the applications of one-pot multisubstrate screenings as a method for developing new synthetic methods.