Effect of Solvents on Proline Modified at the Secondary Sphere: A Multivariate Exploration

Danilo M. Lustosa, Shahar Barkai, Ido Domb, Anat Milo

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

The critical influence of solvent effects on proline-catalyzed aldol reactions has been extensively described. Herein, we apply multivariate regression strategies to probe the influence of different solvents on an aldol reaction catalyzed by proline modified at its secondary sphere with boronic acids. In this system, both in situ binding of the boronic acid to proline and the outcome of the aldol reaction are impacted by the solvent-controlled microenvironment. Thus, with the aim of uncovering mechanistic insight and an ancillary aim of identifying methodological improvements, we designed a set of experiments, spanning 15 boronic acids in five different solvents. Based on hypothesized intermediates or interactions that could be responsible for the selectivity in these reactions, we proposed several structural configurations for the library of boronic acids. Subsequently, we compared the statistical models correlating the outcome of the reaction in different solvents with molecular descriptors produced for each of these proposed configurations. The models allude to the importance of different interactions in controlling selectivity in each of the studied solvents. As a proof-of-concept for the practicality of our approach, the models in chloroform ultimately led to lowering the ketone loading to only two equivalents while retaining excellent yield and enantio-and diastereo-selectivity.

Original languageEnglish
Pages (from-to)1850-1857
Number of pages8
JournalJournal of Organic Chemistry
Volume87
Issue number3
DOIs
StatePublished - 4 Feb 2022

ASJC Scopus subject areas

  • Organic Chemistry

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