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Chemoselective Electrochemical Hydrogenation of Ketones and Aldehydes with a Well‐Defined Base‐Metal Catalyst
Author(s) -
Fokin Igor,
Siewert Inke
Publication year - 2020
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.202002075
Subject(s) - ketone , chemistry , hydride , protonation , catalysis , aldehyde , proton , electrochemistry , alcohol , metal , photochemistry , organic chemistry , electrode , ion , physics , quantum mechanics
Abstract Hydrogenation reactions are fundamental functional group transformations in chemical synthesis. Here, we introduce an electrochemical method for the hydrogenation of ketones and aldehydes by in situ formation of a Mn‐H species. We utilise protons and electric current as surrogate for H 2 and a base‐metal complex to form selectively the alcohols. The method is chemoselective for the hydrogenation of C=O bonds over C=C bonds. Mechanistic studies revealed initial 3 e − reduction of the catalyst forming the steady state species [Mn 2 (H −1 L)(CO) 6 ] − . Subsequently, we assume protonation, reduction and internal proton shift forming the hydride species. Finally, the transfer of the hydride and a proton to the ketone yields the alcohol and the steady state species is regenerated via reduction. The interplay of two manganese centres and the internal proton relay represent the key features for ketone and aldehyde reduction as the respective mononuclear complex and the complex without the proton relay are barely active.