Publication Type Journal Article
Title E-Selective Manganese-Catalyzed Semihydrogenation of Alkynes with H-2 Directly Employed or In Situ-Generated
Authors Ronald A. Farrar-Tobar Stefan Weber Zita Csendes Antonio Ammaturo Sarah Fleissner Helmuth Hoffmann Luis F. Veiros Karl Kirchner
Groups IOARC
Journal ACS CATALYSIS
Year 2022
Month
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Volume 12
Number 4
Pages 2253-2260
Abstract Selective semihydrogenation of alkynes with the Mn(I) alkyl catalyst fac-[Mn(dippe)(CO)(3)(CH2CH2CH3)] (dippe = 1,2-bis(di-iso-propylphosphino)ethane) as a precatalyst is described. The required hydrogen gas is either directly employed or in situ-generated upon alcoholysis of KBH4 with methanol. A series of aryl-aryl, aryl-alkyl, alkyl-alkyl, and terminal alkynes was readily hydrogenated to yield E-alkenes in good to excellent isolated yields. The reaction proceeds at 60 degrees C for directly employed hydrogen or at 60-90 degrees C with in situ-generated hydrogen and catalyst loadings of 0.5-2 mol \%. The implemented protocol tolerates a variety of electron-donating and electron-withdrawing functional groups, including halides, phenols, nitriles, unprotected amines, and heterocycles. The reaction can be upscaled to the gram scale. Mechanistic investigations, including deuterium-labeling studies and density functional theory (DFT) calculations, were undertaken to provide a reasonable reaction mechanism, showing that initially formed Z-isomer undergoes fast isomerization to afford the thermodynamically more stable E-isomer.
DOI http://dx.doi.org/10.1021/acscatal.1c06022
ISBN
Publisher
Book Title
ISSN 2155-5435
EISSN
Conference Name
Bibtex ID WOS:000766237100014
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