An electron-deficient, valine-derived triazolium salt is shown to catalyze a highly chemo- and enantioselective cross-benzoin reaction between aliphatic aldehydes and α-ketoesters. This methodology represents the first high yielding and highly enantioselective intermolecular cross-benzoin reaction using an organocatalyst (up to 94% ee). Further diastereoselective reduction of the products gives access to densely oxygenated compounds with high chemo- and diastereoselectivity.
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Org Lett
May 2024
Nicolaus Copernicus University in Torun, Faculty of Chemistry, 7 Gagarin Street, Torun 87-100, Poland.
This research presents an original method for synthesizing styrylfurans using N-heterocyclic carbenes (NHCs) and Brønsted acid catalysis. By exploiting 2,4-dioxoesters as conjugated 1,3-dicarbonyls, we have developed a technique allowing the efficient formation of highly functionalized styrylfurans with interesting photochemical properties, through a NHC-catalyzed cross-benzoin reaction followed by a Brønsted acid-driven Paal-Knorr-like condensation. This approach permits the integration of various substituents on the furan ring, with preliminary biological studies indicating potential as fluorescent dyes.
View Article and Find Full Text PDFACS Sustain Chem Eng
August 2023
Department of Chemistry, University of Basel, Mattenstrasse 24a, BPR 1096, CH-4058, Basel, Switzerland.
Design of experiments (DoE) plays an important role in optimizing the catalytic performance of chemical reactions. The most commonly used DoE relies on the response surface methodology (RSM) to model the variable space of experimental conditions with the fewest number of experiments. However, the RSM leads to an exponential increase in the number of required experiments as the number of variables increases.
View Article and Find Full Text PDFChem Sci
September 2022
Department of Chemistry, Purdue University West Lafayette Indiana 47907 USA
A dinickel catalyst promotes the [2 + 2 + 1]-cycloaddition of two aldehyde equivalents and a vinylidene. The resulting methylenedioxolane products can be deprotected in one pot under acidic conditions to reveal α-hydroxy ketones. This method provides convenient access to unsymmetrical alkyl-substituted α-hydroxy ketones, which are challenging to synthesize selectively using cross-benzoin reactions.
View Article and Find Full Text PDFOrg Lett
October 2022
Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, Saskatchewan S7N 5C9, Canada.
A route for the synthesis of 1,2,4-triazolium salts via oxidation of a thione precursor is demonstrated. -Pentafluorophenyl-substituted salts are produced in 20-63% overall yields. Isolation and purification of the azolium salts are simplified compared to the traditional synthetic route.
View Article and Find Full Text PDFOrg Lett
June 2021
Department of Materials and Life Sciences, Faculty of Science and Technology, Sophia University, 7-1 Kioicho, Chiyoda-ku, Tokyo 102-8554, Japan.
The utility of acylals as building blocks for selective cross-benzoin synthesis was explored in this study. The synthesis of α-acetoxyketones (-acyl cross-benzoins) was achieved via selective -heterocyclic carbene-catalyzed cross-benzoin reactions using acylals as aldehyde equivalents. Thus, the combination of -substituted phenyl acylals and aromatic/aliphatic aldehydes as coupling substrates using bicyclic triazolium salts as precatalysts and potassium carbonate as a base in THF at reflux temperature selectively yielded -acyl cross-benzoins.
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