56991-23-2Relevant academic research and scientific papers
Cationic NHC-gold(I) complexes: Synthesis, isolation, and catalytic activity
de Frémont, Pierre,Marion, Nicolas,Nolan, Steven P.
experimental part, p. 551 - 560 (2009/06/05)
The reaction of [(NHC)AuCl] complexes (NHC = N-heterocyclic carbene) with a chloride abstractor of the type AgX, where X is a non-coordinating anion, led, in the presence of a neutral coordinating solvent S, to a series of cationic gold(I) complexes of formulae [(NHC)Au(S)]X. Hence, different cationic NHC-gold(I) species bound to acetonitrile, pyridine, 2-Br-pyridine, 3-Br-pyridine, norbornadiene, and THF could be synthesized and characterized by 1H and 13C NMR spectroscopies. Among these, the results of X-ray diffraction studies for [(IPr)Au(NCMe)]SbF6, [(IAd)Au(NCMe)]PF6, [(IPr)Au(pyr)]PF6, [(IPr)Au(2-Br-pyr)]PF6, [(IPr)Au(3-Br-pyr)]PF6 are discussed. As special feature, the structure of [(IPr)Au(2-Br-pyr)]PF6 presented a secondary interaction between the gold and bromine atoms. Additionally, while attempting to obtain crystals of [(IPr)Au(nbd)]PF6, we crystallized a decomposition product featuring a very rare PF4- anion as bridging ligand with formulae [(μ-PF4)((IPr)Au)2]PF4. The observation of a possible P-F bond activation has important implications for cationic Au-based homogeneous catalysis. Finally, we compared the catalytic activities of the different cationic [(NHC)Au(S)]X complexes in the allylic acetate rearrangement reaction and notably observed the inertness of pyridine-based catalysts.
Convenient and efficient Pd-catalyzed regioselective oxyfunctionalization of terminal olefins by using molecular oxygen as sole reoxidant
Mitsudome, Takato,Umetani, Takuya,Nosaka, Naoya,Mori, Kohsuke,Mizugaki, Tomoo,Ebitani, Kohki,Kaneda, Kiyotomi
, p. 481 - 485 (2007/10/03)
(Chemical Equation Presented) Just the one: The combination of palladium dichloride and N,N-dimethylacetamide (DMA) constitutes a highly efficient and reusable catalytic system, which uses molecular oxygen as the sole reoxidant for liquid-phase Wacker oxidation and acetoxylation of terminal olefins to the corresponding methyl ketones and linear allylic acetates, respectively (see scheme). 2006 Wiley-VCH Verlag GmbH Co. KGaA.
Serial ligand catalysis: A highly selective allylic C-H oxidation
Chen, Mark S.,Prabagaran, Narayanasamy,Labenz, Nathan A.,White, M. Christina
, p. 6970 - 6971 (2007/10/03)
We are reporting a mild, chemo-, and highly regioselective Pd(II)-catalyzed allylic oxidation of α-olefins to furnish branched allylic esters that proceeds via a novel serial ligand catalysis mechanism in which two different ligands (i.e., vinyl sulfoxide 2 and BQ) interact sequentially with the metal to promote distinct steps of the catalytic cycle (i.e., C-H cleavage and π-allyl functionalization, respectively). Copyright
A Sulfoxide-Promoted, Catalytic Method for the Regioselective Synthesis of Allylic Acetates from Monosubstituted Olefins via C-H Oxidation
Chen, Mark S.,White, M. Christina
, p. 1346 - 1347 (2007/10/03)
Sulfoxide ligation to Pd(II) salts is shown to selectively promote C-H oxidation versus Wacker oxidation chemistry and to control the regioselectivity in the C-H oxidation products. A catalytic method for the direct C-H oxidation of monosubstituted olefins to linear (E)-allylic acetates in high regio- and stereoselectivities and preparatively useful yields is described. The method using benzoquinone as the stoichiometric oxidant and 10 mol % of Pd(OAc)2 or Pd(O2CCF3)2 as the catalyst in a DMSO/AcOH (1:1) solution was found to be compatible with a wide range of functionality (e.g., amides, carbamates, esters, and ethers, see Table 2). Addition of DMSO was found to be critical for promoting the C-H oxidation pathway, with AcOH alone or in combination with a diverse range of dielectric media, leading to mixtures favoring Wacker-type oxidation products (Tables 1, S3). To explore the role of DMSO as a ligand, the bis-sulfoxide Pd(OAc)2 complex 1 was formed and found to be an effective C-H oxidation catalyst in the absence of DMSO (eqs 2, 3). Moreover, catalyst 1 effects a reversal of regioselectivity, favoring the formation of branched allylic acetates. Copyright
Herstellung und Isomerisierung von 1-Alken-3-yl-acetaten und 2-Alken-1-yl-acetaten
Garcia Martinez, Antonio,Oliver Ruiz, Manuel,Contelles, Jose Luis Marco
, p. 125 - 128 (2007/10/02)
The allylic rearrangement of 1-alken-3-yl acetates in acetic acid containing sodium acetate proceeds at a slower rate but in higher yield than the rearrangement in the presence of strong proton acids.The predominant products are 2-alken-1-yl acetates. (E)-2-Hexen-1-yl acetate can be isomerized to the (Z)-isomer or rearranged to 1-hexen-3-yl acetate via the epoxide, depending upon the conditions of reduction of the epoxide.
