Chromium-Catalyzed Alkylation of Amines by Alcohols

Titelangaben

Kallmeier, Fabian ; Fertig, Robin ; Irrgang, Torsten ; Kempe, Rhett:
Chromium-Catalyzed Alkylation of Amines by Alcohols.
In: Angewandte Chemie International Edition. Bd. 59 (2020) Heft 29 . - S. 11789-11793.
ISSN 1521-3773
DOI der Verlagsversion: https://doi.org/10.1002/anie.202001704

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Abstract

The alkylation of amines by alcohols is a broadly applicable, sustainable, and selective method for the synthesis of alkyl amines, which are important bulk and fine chemicals, pharmaceuticals, or agrochemicals. Here we report that Cr complexes can catalyze this C‐N bond formation reaction. We synthesized and isolated 35 examples of alkylated amines. Thirteen previously undisclosed products could be obtained and the use of amino alcohols as alkylating agents could be demonstrated. The catalyst tolerates numerous functional groups, among them hydrogenation sensitive examples. In comparison to many other alcohol‐based amine alkylation protocols where a stoichiometric amount of base is required, our Cr based catalyst system permits product isolation with yields higher than 90% for various alkyl amines with a catalytic amount of base only. Our study indicates that Cr complexes can catalyze borrowing hydrogen or hydrogen auto‐transfer reactions and, thus, could be an alternative to Fe, Co and Mn or noble metals in (de)hydrogenation catalysis.