An examination of the palladium/Mor-DalPhos catalyst system in the context of selective ammonia monoarylation at room temperature.

Autor: Alsabeh PG; Department of Chemistry, Dalhousie University, 6274 Coburg Road, PO Box 15000, Halifax, Nova Scotia B3H 4R2, Canada., Lundgren RJ, McDonald R, Johansson Seechurn CC, Colacot TJ, Stradiotto M
Jazyk: angličtina
Zdroj: Chemistry (Weinheim an der Bergstrasse, Germany) [Chemistry] 2013 Feb 04; Vol. 19 (6), pp. 2131-41. Date of Electronic Publication: 2013 Jan 04.
DOI: 10.1002/chem.201203640
Abstrakt: An examination of the [{Pd(cinnamyl)Cl}(2)]/Mor-DalPhos (Mor-DalPhos = di(1-adamantyl)-2-morpholinophenylphosphine) catalyst system in Buchwald-Hartwig aminations employing ammonia was conducted to better understand the catalyst formation process and to guide the development of precatalysts for otherwise challenging room-temperature ammonia monoarylations. The combination of [{Pd(cinnamyl)Cl}(2)] and Mor-DalPhos afforded [(κ(2)-P,N-Mor-DalPhos)Pd(η(1)-cinnamyl)Cl] (2), which, in the presence of a base and chlorobenzene, generated [(κ(2)-P,N-Mor-DalPhos)Pd(Ph)Cl] (1 a). Halide abstraction from 1 a afforded [(κ(3)-P,N,O-Mor-DalPhos)Pd(Ph)]OTf (5), bringing to light a potential stabilizing interaction that is offered by Mor-DalPhos. An examination of [(κ(2)-P,N-Mor-DalPhos)Pd(aryl)Cl] (1 b-f) and related precatalysts for the coupling of ammonia and chlorobenzene at room temperature established the suitability of 1 a in such challenging applications. The scope of reactivity for the use of 1 a (5 mol %) encompassed a range of (hetero)aryl (pseudo)halides (X = Cl, Br, I, OTs) with diverse substituents (alkyl, aryl, ether, thioether, ketone, amine, fluoro, trifluoromethyl, and nitrile), including chemoselective arylations.
(Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)
Databáze: MEDLINE
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