A metal-free generation of carbanion nucleophiles is of prime importance in organic synthesis. Herein we report a photocatalytic approach to the Corey-Seebach reaction. The presented method operates under mild redox-neutral and base-free conditions giving the desired product with high functional group tolerance. The reaction is enabled by the combination of photo- and hydrogen atom transfer (HAT) catalysis. This catalytic merger allows a C-H to carbanion activation by the abstraction of a hydrogen atom followed by radical reduction. The generated nucleophilic intermediate is then capable of adding to carbonyl electrophiles. The obtained dithiane can be easily converted to the valuable α-hydroxy carbonyl in a subsequent step. The proposed reaction mechanism is supported by emission quenching, radical-radical homocoupling and deuterium labeling studies as well as by calculated redox-potentials and bond strengths.
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http://dx.doi.org/10.1002/chem.202003000 | DOI Listing |
Molecules
May 2023
Department of Chemistry, Siedlce University of Natural Sciences and Humanities, 3-Go Maja 54, 08-110 Siedlce, Poland.
ACS Omega
October 2022
Institute of Inorganic Chemistry, Graz University of Technology, Stremayrgasse 9/IV, 8010 Graz, Austria.
In this study, a variety of α,ω-bisacylpolysilanes were synthesized via two synthetic protocols. The first method for obtaining these compounds is based on the substitution reaction of bromine either on silica gel or by the use of silver salts. Surprisingly, instead of the expected bromine substitution product PhC(O)(SiMe)C(O)Ph , we found the formation of the diastereomer PhC(O)(SiMe)CBrPhOCBrPh(SiMe)C(O)Ph indicating a more complex reaction cascade.
View Article and Find Full Text PDFChemistry
December 2022
Department of Pharmaceutical Sciences, University of Vienna, Josef-Holaubek-Platz 2, 1090, Vienna, Austria.
Due to their high stability towards enzymatic hydrolysis C-acyl glycosidic compounds are useful synthetic intermediates for potential candidates in drug discovery. Syntheses for C-acyl mannosides have remained scarce and usually employ donors obtained from lengthy syntheses. Furthermore, syntheses of unprotected C-acyl mannosides have not been reported so far, due to the incapability of the C-acyl mannoside motif with deprotection conditions for protective groups commonly used in carbohydrate chemistry.
View Article and Find Full Text PDFDalton Trans
September 2021
Institute of Inorganic Chemistry, Technical University Graz, Stremayrgasse 9/IV, 8010 Graz, Austria.
Acylgermanes are known as highly efficient photoinitiators. In this contribution, we present the synthesis of new diacylgermanes 4a-evia a multiple silyl abstraction methodology. The method outperforms the state-of-the-art approach (Corey-Seebach reaction) towards diacylgermanes in terms of group tolerance and toxicity of reagents.
View Article and Find Full Text PDFChemistry
October 2020
Department of Organic Chemistry, University of Regensburg, Universitätsstraße 31, 93053, Regensburg, Germany.
A metal-free generation of carbanion nucleophiles is of prime importance in organic synthesis. Herein we report a photocatalytic approach to the Corey-Seebach reaction. The presented method operates under mild redox-neutral and base-free conditions giving the desired product with high functional group tolerance.
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