851487-54-2Relevant articles and documents
Diaminocarbene- and Fischer-carbene complexes of palladium and nickel by oxidative insertion: Preparation, structure, and catalytic activity
Kremzow, Doris,Seidel, Guenter,Lehmann, Christian W.,Fuerstner, Alois
, p. 1833 - 1853 (2007/10/03)
Oxidative insertion of [Pd(PPh3)4] or [Ni(cod) 2]/PPh3 into the C-Cl bond of various 2- chloroimidazolinium- and other -amidinium salts affords metal-diaminocarbene complexes in good to excellent yields. This procedure is complementary to existing methodology in which the central metal does not change its oxidation state, and therefore allows to incorporate carbene fragments that are difficult to access otherwise. The preparation of a variety of achiral as well as enantiomerically pure, chiral metal-NHC complexes (NHC = N-heterocyclic carbene) and metal complexes with acyclic diaminocarbene ligands illustrates this aspect. Furthermore it is shown that oxidative insertion also paves a way to prototype Fischer carbenes of PdII. Since the required starting materials are readily available from urea- or thiourea derivatives, this novel approach allows for substantial structural variations of the ligand backbone. The catalytic performance of the resulting library of nickel- and palladium-carbene complexes has been evaluated by applications to prototype Suzuki-, Heck-, and Kumada-Corriu cross-coupling reactions as well as Buchwald-Hartwig aminations. It was found that even Fischer carbenes show appreciable catalytic activity. Moreover, representative examples of all types of neutral and cationic metal-carbene complexes formed in this study have been characterized by X-ray crystallography.
Synthesis and structure of highly polarised double-bond compounds derived from S-proline
Aitken,Ali,De Elena,Lightfoot
, p. 7965 - 7968 (2007/10/03)
Reaction of the chiral iminium salt 3 with stabilised carbanions gives the compounds 4-9 containing a highly polarised double bond. The extent of this polarisation is determined by variable temperature 1H NMR studies, comparison of 13C NMR chemical shifts and an X-ray structure determination. (C) 2000 Elsevier Science Ltd.
