12203-31-5Relevant articles and documents
Palladium-catalyzed allylic substitution with (η6-Arene- CH2Z)Cr(CO)3-based nucleophiles
Zhang, Jiadi,Stanciu, Corneliu,Wang, Beibei,Hussain, Mahmud M.,Da, Chao-Shan,Carroll, Patrick J.,Dreher, Spencer D.,Walsh, Patrick J.
, p. 20552 - 20560 (2012/02/13)
Although the palladium-catalyzed Tsuji-Trost allylic substitution reaction has been intensively studied, there is a lack of general methods to employ simple benzylic nucleophiles. Such a method would facilitate access to "α-2-propenyl benzyl" motifs, which are common structural motifs in bioactive compounds and natural products. We report herein the palladium-catalyzed allylation reaction of toluene-derived pronucleophiles activated by tricarbonylchromium. A variety of cyclic and acyclic allylic electrophiles can be employed with in situ generated (η6-C 6H5CHLiR)Cr(CO)3 nucleophiles. Catalyst identification was performed by high throughput experimentation (HTE) and led to the Xantphos/palladium hit, which proved to be a general catalyst for this class of reactions. In addition to η6-toluene complexes, benzyl amine and ether derivatives (η6-C6H5CH 2Z)Cr(CO)3 (Z = NR2, OR) are also viable pronucleophiles, allowing C-C bond-formation α to heteroatoms with excellent yields. Finally, a tandem allylic substitution/demetalation procedure is described that affords the corresponding metal-free allylic substitution products. This method will be a valuable complement to the existing arsenal of nucleophiles with applications in allylic substitution reactions.
Heterogeneous and homogeneous hydrogenation of styrene and stilbene chromium tricarbonyl complexes
Artemov,Sazonova,Lomakin
, p. 45 - 48 (2008/02/11)
Heterogeneous hydrogenation of the styrene and stilbene chromium tricarbonyl complexes by molecular hydrogen on skeletal nickel and palladium on carbon as catalysts was studied. As compared to styrene and stilbene, their arene chromium tricarbonyl analogs
Benzylic functionalization of (η6-alkylarene)chromium tricarbonyl complexes
Kalinin, Valery N.,Cherepanov, Il'ya A.,Moiseev, Sergey K.
, p. 437 - 455 (2007/10/03)
A general method for the regioselective benzylic metallation of (η6-alkylarene)chromium tricarbonyl complexes on the action of lithium amides in THF under very mild conditions has been developed. Transmetallation reactions of the lithium derivatives thus obtained produce the corresponding benzylic organotin, zinc and copper chromium tricarbonyl complexes. Methods for the preparative benzylic functionalization of (η6-alkylarene)chromium tricarbonyl complexes have been developed, including carboxylation, α-hydroxyalkylation, γ-carbonylation, acylation, arylation, vinylation, heteroarylation and alkylation procedures. 5-Acetoxy-3-benzyl-1,4-methano-2,3,4,5-tetrahydro-1H-3-benzazepine has been prepared using the benzylic lithium derivative of the (η6-alkylarene)chromium tricarbonyl complex at the key step. This compound is a representative of the major class of physiologically active compounds known as C-norbenzomorphans.
Addition de Carbanions α Benchrotreniques sur Divers Aldehydes non Enolisables; Evolution des Produits Primaires d'Addition par Oxidation d'Oppenauer-Woodward, influence de la Substitution
Senechal-Tocquer, M. C.,Senechal, D.,Bihan, J. Y. Le,Gentric, D.,Caro, B.
, p. 353 - 364 (2007/10/02)
Aromatic hydrocarbons complexed with a Cr(CO)3 unit react with benzaldehydes and furfural in THF and in presence of t-BuOK at the benzylic position to give condensation products in good yields.Formation of ketones by in situ Oppenauer-Woodward oxidation is observed.Influence of ring substituents on this formation is discussed.
Intramolecular vibrational relaxation in n-alkyl benzene chromium tricarbonyls: State selective production of chromium atoms
Hossenlopp, Jeanne M.,Samoriski, Brian,Rooney, Dan,Chaiken, J.
, p. 3331 - 3337 (2007/10/02)
We have measured one color multiphoton dissociation/ionization (MPD/MPI) spectra for a series of n-alkyl substituted arene chromium tricarbonyls (ACTs) .Our data indicate that intramolecular vibrational relaxation (IVR) rates for methyl, ethyl, and propyl ACTs increase relative to the benzene analog in the ratio of 3:6:34.In contrast, the net relaxation rates of the p-xylene (dimethyl) and mesitylene (trimethyl) analogs are two and three times faster than benzene, respectively.The behavior of these latter analogs probably also reflects differences in electronic structure relative to the benzene ACT.Taken with the results of experiments on other analogs and the independently obtained results on the uncomplexed arenes, we have found a strong correlation between the presence of low frequency vibrations and the rate of IVR.The rate of IVR determines the distribution of neutral chromium atoms formed by MPD of the n-alkyl ACTs.
