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Most Requested Journal Articles 3Q06-Chemistry and Related Science

Following is one of the journal articles most requested by researchers using CAS electronic products.

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CAS indexed 92 chemical substances from this document. CAS subject entries for this document include: Amines, preparation; Amination; Amination catalysts; and 7 additional concepts.

CAPLUS COPYRIGHT 2006 ACS on STN

TITLE:	Modified (NHC)Pd(allyl)Cl (NHC = N-Heterocyclic Carbene) Complexes for Room-Temperature Suzuki-Miyaura and Buchwald-Hartwig Reactions
AUTHOR(S):	Marion, Nicolas; Navarro, Oscar; Mei, Jianguo; Stevens, Edwin D.; Scott, Natalie M.; Nolan, Steven P.
CORPORATE SOURCE:	Department of Chemistry, University of New Orleans, New Orleans, LA, 70148, USA
SOURCE:	Journal of the American Chemical Society (2006), 128(12), 4101-4111 CODEN: JACSAT; ISSN: 0002-7863
PUBLISHER:	American Chemical Society
LANGUAGE:	English

ABSTRACT:
A series of heterocyclic carbene complexes (NHC)Pd(R-allyl)Cl complexes [NHC = N,N'-bis(2,6-diisopropylphenyl)imidazol-2-ylidene, N,N'-bis(2,6-diisopropylphenyl)-4,5-dihydroimidazol-2-ylidene; R = H, Me, gem-Me2, Ph] have been synthesized and fully characterized. When compared to (NHC)Pd(allyl)Cl, substitution at the terminal position of the allyl scaffold favors a more facile activation step. This translates into higher catalytic activity in the Suzuki-Miyaura and Buchwald-Hartwig reactions, allowing for the coupling of unactivated aryl chlorides at room temp. in minutes. In the Suzuki-Miyaura reaction, aryl triflates, bromides, and chlorides react with boronic acids using very low catalyst loading. In the N-aryl amination reaction, a wide range of substrates has been coupled efficiently; primary and secondary alkyl- or aryl-amines react in high yields with unactivated, neutral, and activated aryl chlorides and bromides. In both reactions, extremely hindered substrates such as tri-ortho-substituted biaryls and tetra-ortho-substituted diarylamines can be produced without loss of activity. Finally, the present catalytic system has proven to be efficient with as low as 10 parts-per-million (ppm) of precatalyst in the Buchwald-Hartwig reaction and 50 ppm in the Suzuki-Miyaura reaction.