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Direct Amination of Alcohols Catalyzed by Aluminum Triflate: An Experimental and Computational Study
Author(s) -
Payard PierreAdrien,
Gu Qingyi,
Guo Wenping,
Wang Qianran,
Corbet Matthieu,
Michel Carine,
Sautet Philippe,
Grimaud Laurence,
Wischert Raphael,
PeraTitus Marc
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.201801492
Subject(s) - nitromethane , amination , chemistry , catalysis , trifluoromethanesulfonate , aniline , reactivity (psychology) , toluene , solvent , homogeneous catalysis , organic chemistry , alternative medicine , pathology , medicine
Among the best‐performing homogeneous catalysts for the direct amination of activated secondary alcohols with electron‐poor amine derivatives, metal triflates, such as aluminum triflate, Al(OTf) 3 , stand out. Herein we report the extension of this reaction to electron‐rich amines and activated primary alcohols. We provide detailed insight into the structure and reactivity of the catalyst under working conditions in both nitromethane and toluene solvent, through experiment (cyclic voltammetry, conductimetry, NMR spectroscopy), and density functional theory (DFT) simulations. Competition between aniline and benzyl alcohol for Al in the two solvents explains the different reactivities. The catalyst structures predicted from the DFT calculations were validated by the experiments. Whereas a S N 1‐type mechanism was found to be active in nitromethane, we propose a S N 2 mechanism in toluene to rationalize the much higher selectivity observed when using this solvent. Also, unlike what is commonly assumed in homogeneous catalysis, we show that different active species may be active instead of only one.