Mathematical relationships that relate chemical structure with selectivity have provided quantitative insights underlying catalyst design and informing mechanistic studies. However, flexible compounds can adopt several distinct geometries and can be challenging to describe, using a single structure-based descriptor. How best to quantify the structural characteristics of an ensemble of structure poses both practical and technical difficulties. In this work, we introduce an automated computational workflow that can be used to obtain multidimensional Sterimol parameters for a conformational ensemble of a given substituent from a single command. The Boltzmann-weighted Sterimol parameters obtained from this approach are shown to be useful in multivariate models of enantioselectivity, while the range of values from conformers within 3 kcal/mol of the most stable structure provides a visual way to capture a possible source of uncertainty arising in the resulting models for enantioselectivity. Our approach improves the model performance in cases where particularly flexible substituents have been studied. In all cases, this approach enables the impact of conformational effects on model performance to be quickly diagnosed: in particular, these effects may be more significant than statistical model error such that selectivity prediction should be performed more cautiously. Implementing our approach requires no programming expertise and can be executed from within a graphical user interface using open-source programs.

<div> <div> <div> <p>Mathematical relationships which relate chemical structure with selectivity have provided quantitative insights underlying catalyst design and informing mechanistic studies. Flexible compounds, however, can adopt several distinct geometries and so can be challenging to describe using a single structure-based descriptor. How best to quantify the structural characteristics of an ensemble of structure poses both practical and technical difficulties. In this work we introduce an automated computational workflow which can be used to obtain multidimensional Sterimol parameters for a conformational ensemble of a given substituent from a single command. The Boltzmann-weighted Sterimol parameters obtained from this approach are shown to be useful in multivariate models of enantioselectivity, while the range of values from conformers within 3 kcal/mol of the most stable structure provides a visual way to capture a possible source of uncertainty arising in the resulting models. Implementing our approach requires no programming expertise and can be executed from within a graphical user interface using open-source programs. </p> </div> </div> </div>

The development of catalytic enantioselective methods is routinely carried out using easily accessible and prototypical substrates. This approach to reaction development often yields asymmetric methods that perform poorly using substrates that are sterically or electronically dissimilar to those used during the reaction optimization campaign. Consequently, expanding the scope of previously optimized catalytic asymmetric reactions to include more challenging substrates is decidedly nontrivial. Here, we address this challenge through the development of a systematic workflow to broaden the applicability and reliability of asymmetric conjugate additions to substrates conventionally regarded as sterically and electronically demanding. The copper-catalyzed asymmetric conjugate addition of alkylzirconium nucleophiles to form tertiary centers, although successful for linear alkyl chains, fails for more sterically demanding linear α,β-unsaturated ketones. Key to adapting this method to obtain high enantioselectivity was the synthesis of modified phosphoramidite ligands, designed using quantitative structure–selectivity relationships (QSSRs). Iterative rounds of model construction and ligand synthesis were executed in parallel to evaluate the performance of 20 chiral ligands. The copper-catalyzed asymmetric addition is now more broadly applicable, even tolerating linear enones bearing tert-butyl β-substituents. The presence of common functional groups is tolerated in both nucleophiles and electrophiles, giving up to 99% yield and 95% ee across 20 examples.