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Mechanistic Insights on the Ruthenium‐Catalyzed Hydrogenation of Amides – C–N vs. C–O Cleavage
Author(s) -
Cantillo David
Publication year - 2011
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201100443
Subject(s) - chemistry , ruthenium , cleavage (geology) , tautomer , imine , amide , pincer movement , catalysis , transition state , aromatization , selectivity , stereochemistry , medicinal chemistry , organic chemistry , geotechnical engineering , fracture (geology) , engineering
Abstract Ruthenium‐catalyzed amide hydrogenation was thoroughly explored by means of DFT calculations. All the plausible pathways, including those involving the amide or imine tautomer, were assessed. The classical C–O cleavage and the recently reported C–N cleavage were compared by employing a bipyridyl‐based Ru II pincer complex as catalyst in the calculations. The study reveals that C–O cleavage can be achieved directly over the amide substrate or its imine tautomer, since the computed pathways show analogous energy barriers. In addition, the mechanism for the novel C–N cleavage was elucidated by modeling all the reasonable intermediates and transition structures. The computed energy barrier is lower than that for C–O cleavage by more than 10 kcal mol –1 , thus explaining the observed selectivity. The key role of the aromatization/dearomatization processes during the transformation is also disclosed.