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Selective Base‐free Transfer Hydrogenation of α,β‐Unsaturated Carbonyl Compounds using i PrOH or EtOH as Hydrogen Source
Author(s) -
FarrarTobar Ronald A.,
Wei Zhihong,
Jiao Haijun,
Hinze Sandra,
de Vries Johannes G.
Publication year - 2018
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.201705423
Subject(s) - crotonaldehyde , chemistry , dehydrogenation , catalysis , transfer hydrogenation , selectivity , allylic rearrangement , hydrogen , base (topology) , kinetics , combinatorial chemistry , organic chemistry , medicinal chemistry , mathematical analysis , physics , mathematics , quantum mechanics , ruthenium
Commercially available Ru‐MACHO TM ‐BH is an active catalyst for the hydrogenation of several functional groups and for the dehydrogenation of alcohols. Herein, we report on the new application of this catalyst to the base‐free transfer hydrogenation of carbonyl compounds. Ru‐MACHO TM ‐BH proved to be highly active and selective in this transformation, even with α,β‐unsaturated carbonyl compounds as substrates. The corresponding aliphatic, aromatic and allylic alcohols were obtained in excellent yields with catalyst loadings as low as 0.1–0.5 mol % at mild temperatures after very short reaction times. This protocol tolerates i PrOH and EtOH as hydrogen sources. Additionally, scale up to multi‐gram amounts was performed without any loss of activity or selectivity. An outer‐sphere mechanism has been proposed and the computed kinetics and thermodynamics of crotonaldehyde and 1‐phenyl‐but‐2‐en‐one are in perfect agreement with the experiment.