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Direct Stereodivergent Olefination of Carbonyl Compounds with Sulfur Ylides

Jérémy Merad, Phillip S. Grant, Tobias Stopka, Juliette Sabbatani, Ricardo Meyrelles, Alexander Preinfalk, Ján Matyasovsky, Boris Maryasin, Leticia González and Nuno Maulide*

*Institute of Organic Chemistry, University of Vienna, 1090 Vienna, Austria, Email:

J. Merad, P. S. Grant, T. Stopka, J. Sabbatani, R. Meyrelles, A. Preinfalk, J. Matyasovsky, B. Maryasin, L. González, N. Maulide, J. Am. Chem. Soc., 2022, 144, 12536-12543.

DOI: 10.1021/jacs.2c05637

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Thiouronium ylides are valuable olefination reagents for stereodivergent carbonyl olefinations. Using these reagents, aldehydes are converted to Z-alkenes with high stereoselectivity and broad substrate scope, while N-tosylimines provide a similarly proficient entry to E-alkenes. In-depth computational and experimental studies clarified the mechanistic details of this unusual reactivity.

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Energy profile of the C-C coupling of ylide with tosyl imine

E-selective olefination of N-tosylimines

The respective aldimine (0.20 mmol, 1.0 eq) and the sulfonium salt (0.22 mmol, 1.1 eq) were dissolved in dry CHCl3 (2 mL, 0.1 M) and cooled to -78 °C. Barton's base (0.24 mmol, 1.2 eq) was added dropwise and the reaction mixture was stirred at -78 °C for 2 h, then was allowed to reach rt over the course of 12 h. A solution of sat. aq. NH4Cl was added and the aq. phase was extracted with dichloromethane (3 × 20 ml). The combined organic layers were dried over magnesium sulfate and the solvent removed under reduced pressure. The crude residue* was purified by column chromatography.

*In all cases, 1H NMR analysis of the crude reaction mixture indicated a >20:1 E/Z ratio

Key Words

E-alkenes, unsaturated esters

ID: J48-Y2022