Room-Temperature Chemoselective Reductive Alkylation of Amines Catalyzed by a Well-Defined Iron(II) Complex Using Hydrogen

Abstract : A transition-metal frustrated Lewis pair approach has been envisaged to enhance the catalytic activity of tricarbonyl phosphine-free iron complexes in reduction of amines. A new cyclopentadienyl iron(II) tricarbonyl complex has been isolated, fully characterized, and applied in hydrogenation. This phosphine-free iron complex is the first Earth-abundant metal complex that is able to catalyze chemoselective reductive alkylation of various functionalized amines with functionalized aldehydes. Such selectivity and functionality tolerance (alkenes, esters, ketones, acetals, unprotected hydroxyl groups, and phosphines) have been demonstrated also for the first time at room temperature with an Earth-abundant metal complex. This alkylation reaction was also performed without any preliminary condensation and generated only water as a byproduct. The resulting amines provided rapid access to potential building blocks, metal ligands, or drugs. Density functional theory calculations highlighted first that the formation of the 16 electron species, via the activation of the tricarbonyl complex Fe3, was facilitated and, second, that the hydrogen cleavage did not follow the same pathway as bond breaking, usually described with the known cyclopentadienone iron tricarbonyl complexes (Fe1 and Fe4). These calculations highlighted that the new complex Fe3 does not behave as a bifunctional catalyst, in contrast to its former congeners.
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https://hal-normandie-univ.archives-ouvertes.fr/hal-02159908
Contributeur : Jean-Luc Renaud <>
Soumis le : mercredi 19 juin 2019 - 10:20:47
Dernière modification le : mardi 8 octobre 2019 - 13:52:02

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Alexis Lator, Quentin Gaignard Gaillard, Delphine Merel, Jean-François Lohier, Sylvain Gaillard, et al.. Room-Temperature Chemoselective Reductive Alkylation of Amines Catalyzed by a Well-Defined Iron(II) Complex Using Hydrogen. Journal of Organic Chemistry, American Chemical Society, 2019, 84 (11), pp.6813-6829. ⟨10.1021/acs.joc.9b00581⟩. ⟨hal-02159908⟩

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