Palladium arene olefination

Muller TJJ (2006) Sequentially Palladium-Catalyzed Processes. 19 149-206 Mulzer J, Ohler E (2004) Olefin Metathesis in Natural Product Syntheses. 13 269-366 Muniz K (2004) Planar Chiral Arene Chromium (0) Complexes as Ligands for Asymetric Catalysis. 7 205-223 Murai S, see Kakiuchi F (1999) 3 47-79... 

Density functional theory studies arene chromium tricarbonyls, 5, 255 beryllium monocyclopentadienyls, 2, 75 chromium carbonyls, 5, 228 in computational chemistry, 1, 663 Cp-amido titanium complexes, 4, 464—465 diiron carbonyl complexes, 6, 222 manganese carbonyls, 5, 763 molybdenum hexacarbonyl, 5, 392 and multiconfiguration techniques, 1, 649 neutral, cationic, anionic chromium carbonyls, 5, 203-204 nickel rj2-alkene complexes, 8, 134—135 palladium NHC complexes, 8, 234 Deoxygenative coupling, carbonyls to olefins, 11, 40 (+)-4,5-Deoxyneodolabelline, via ring-closing diene metathesis, 11, 219... 

The C-H/olefin coupling of aryloxazolines proceeds with unusual product selectivity. In this case, alkylation products, i.e., formally dehydrogenation products, are obtained as a major product (Eq. 22) [11]. These types of dehydrogenation compounds are believed to be formed via a carbometalation pathway. The first example of this type of alkenylation of arenes with olefins using palladium(II) complexes via C-H bond cleavage was reported in 1967 [32]. Later, several efforts were made to perform this reaction in a catalytic manner [33]. In 2001, Milstein et al. [34] reported the oxidative alkenylation of arenes with olefins using a Ru/02/C0 catalyst system (Eq. 23). Details of the reaction mechanism have not been elucidated. 

Laboratory in Oxford, and Geoffrey Ozin at the University of Toronto in the early 1970s. With the metal atom cocondensation technique (which as described in Chaps. 6 and 7 was also used to prepare a series of zerovalent arene and olefin metal complexes), they reported simultaneously that the elusive palladium and platinum tetracarbonyls, Pd(CO)4 and Pt(CO)4, as well as the coordinatively unsaturated fragments M(CO)3, M(CO)2, and M(CO) (M = Pd, Pt) were formed by cocondensation reactions of Pd and Pt atoms with CO in inert gas matrices at 4-10 K [119-122]. The comparison of the CO bond stretching force constants for Pd(CO)ra and Pt(CO)ra (n - 1-4) revealed that, in analogy to Ni(CO) , the most stable compounds were the tetracarbonyls. In a xenon matrix, Pd(CO)4 existed up to about 80 K [120]. Ozin s group as well as others... 

More recently, cationic intermediates have been observed in the Heck reactions of arene diazonium salts catalyzed by triolefinic macrocycle Pd(0) complexes [17,59], o-iodophenols and enoates to form new lactones [60], and o-iodophenols with olefins (the oxa-Heck reaction) [61 ]. In the first case ions were formed by oxidation of the analyte at the capillary, or by association of [NH4] or Na". In the two other cases ionization occurred through the more typical loss of a halide ligand. The oxa-Heck reaction provides a good example of how these experiments are typically performed and the type of information that can be obtained. The oxyarylations of olefins were performed in acetone, catalyzed by palladium, and required the presence of sodium carbonate as base. Samples from the reaction mixtures were diluted with acetonitrile and analyzed by ESI(+)-MS. Loss of iodide after oxidative addition of o-iodophenol to palladium afforded positively-charged intermediates. Species consistent with oxidative addition, such as [Pd(PPh3)2(C6H50)], and the formation of palladacycles of the type seen in Scheme 8 were observed. Based on this, a mechanism for the reaction was proposed (Scheme 8). 

An interesting application of the Fujiwara-Moritani/oxidative Heck reaction for the synthesis of benzo furans was recently reported by the Stoltz lab [31]. A variety of allyl phenyl ethers (all containing electron-rich aryl components) react with 10 mol% palladium acetate, 20 mol% ethyl nicotinate, 20 mol% sodium acetate, and one equivalent of benzoquinone at 100°C to provide benzofurans in 52-79% yield (e.g. 16—>17). The mechanism of this transformation begins with arene palladation of Pd(II) followed by olefin insertion, p-hydrogen elimination, and olefin isomerization to the thermodynamically favored benzofuran product. The resulting Pd(0) species is then oxidized to Pd(ll) thus regenerating the active catalyst. 

Fujiwara and Moritoni carried out seminal work in the area of C-H alkenylation they reported that palladium(II) complexes could mediate the coupling of unfunctionalized arenes with olefins in refluxing acetic acid [64]. The initial reactions used stoichiometric quantities of palladium salts however the reaction was subsequently... 

Nucleophilic attack of the arene on the palladium-olefin complex I with loss of HCI... 

Tanaka D, Romeril ASP, Myers AG (2005) On the mechanism of the palladium(II)-catalyzed decarboxylative olefination of arene carboxylic acids. Crystallographic characterization of non-phosphine palladium(II) intermediates and observation of their stepwise transformation in Heck-like processes. J Am Chem Soc 127 10323-10333... 

Water-in-C02 microemulsions with diameters in the order of several nanometers are prepared by a mixture of AOT and a Pn E-P04 co-surfactant. The CO2 microemulsions allow metal species to be dispersed in the nonpolar supercritical CO2 phase. By chemical reduction, metal ions dissolved in the water core of the microemulsion can be reduced to the elemental state forming nanoparticles with narrow size distribution. The palladium and rhodium nanoparticles produced by hydrogen reduction of Pd and Rh ions dissolved in the water core are very effective catalysts for hydrogenation of olefins and arenes in supercritical CO2. 

The nucleophilic addition to polyene (e.g., alkene, diene, arene) and polyenyl (e.g., allyl, cyclopentadienyl) ligands has contributed significantly to the numerous and unique applications organometallic reagents have in organic synthesis. The catalytic oxidation of olefins to carbonyl compounds (e.g., the palladium-mediated conversion... 

For reviews on the Fujiwara-Moritani reaction, see (a) Fujiwara, Y. (2002) Palladium-promoted alkene-arene coupling via C—H activation, in Handbook of Organopalladium Chemistry in Organic Synthesis, Vol. 2 (eds E.-i. Negishi and A. de Meijere), John Wiley Sons, Inc., New York, pp. 2863-71 (b) Jia, C., Kitamura, T. and Fujiwara, Y. (2001) Catalytic functionalization of arenes and alkanes via C—H bond activation. Acc. Chem. Res., 34, 633-9 (c) Fujiwara, Y. and Jia, C. (2001) New developments in transition metal-catalyzed synthetic reactions viaC—H bond activation. PureAppl. Chem., 73,319-24 (d) Moritani, I. and Fujiwara, Y. (1973) Aromatic substitution of olefins by palladium salts. Synthesis, 524-33. 

The intermolecular oxidative arylation of olefins has been reported in most cases with acrylic acid derivatives. This process could be developed as an alternative to the Heck reaction, which occurs with aryl halides. Several groups have reported versions of this oxidative C-C bond formation. Fujiwara reported intermolecular examples of this reaction catalyzed by palladium and copper (Equation 18.64). Intermolecular versions of this reaction have also been reported with ruthenium catalysts and as the oxidant. Other oxidative reactions in which electron-rich arenes add to olefins (Equation 18.66) have been reported as stoidiiometric steps of natural products syntheses, and later as a catalytic process. ... 

Similar palladium-catalyzed cascade arylations also occur with acyclic alkenes, including a,p-unsaturated sulfones (Equation 19.153), sulfonamides, phosphine oxides, and phosphonate esters. In contrast, typical conjugated olefins, such as a, 3-unsaturated esters and enones almost exclusively react to form products from Heck reactions. Direct arylations have also been conducted with disubstituted alkynes containing a terminal arene and a large group, such as an aryl or ferf-butyl group (Equation 19.154). ... 

In [51], Wacker oxidation of olefins was studied in the presence of catalytic systems comprising water-soluble calixarenes (sulfonated and glycydylated derivatives), palladium salt, and copper salt. The presence of nonpolar cavities in these molecules enables binding nonpolar substrates and their transfer into the aqueous phase where the reaction takes place. The activity of these catalysts depends on the complementarity between the cavity size of the host molecule and the size of the guest molecule. Therefore, substrate selectivity was exhibited. For example, the addition of calixarene increased the reaction rate for linear 1-alkenes which size corresponded to the size of the calixarene cavity (1-hexene for calix[4]arene and 1-octene for calix[6]arene). The activity of catalytic system applied for the oxidation of substituted styrenes also depended on the ratio of the size of the substrate molecule and that of the calixarene cavity. 

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