Transition metal-promoted

Eithei oxidation state of a transition metal (Fe, Mn, V, Cu, Co, etc) can activate decomposition of the hydiopeioxide. Thus a small amount of tiansition-metal ion can decompose a laige amount of hydiopeioxide. Trace transition-metal contamination of hydroperoxides is known to cause violent decompositions. Because of this fact, transition-metal promoters should never be premixed with the hydroperoxide. Trace contamination of hydroperoxides (and ketone peroxides) with transition metals or their salts must be avoided. 

Ketone Peroxides. These materials are mixtures of compounds with hydroperoxy groups and are composed primarily of the two stmctures shown in Table 2. Ketone peroxides are marketed as solutions in inert solvents such as dimethyl phthalate. They are primarily employed in room-temperature-initiated curing of unsaturated polyester resin compositions (usually containing styrene monomer) using transition-metal promoters such as cobalt naphthenate. Ketone peroxides contain the hydroperoxy (—OOH) group and thus are susceptible to the same ha2ards as hydroperoxides. 

Selective transition metal-promoted carbon-carbon bond formation in polyhalo-hetarenes 970PP137. 

Nelson J. H. Transition Metal-Promoted Intramolecular [4 + 2 Diels-Alder Cycloadditions of Phospholes With Dienophilic Ligands in Phosphorus-31 NMR Spectral Prop. Compd. Charact. Struct. Anal. 1994 203, Ed. Quin L. and Verkade J. G., Pb. VCH N.Y. 

Catalytic quantities of transition- or non-transition metals promote the cyclization of 2-alkynynylbiphenyl analogs to phenanthrene or fulvene analogs. The mechanism is thought to involve activation of the alkyne by metal coordination, prior to cyclization (Equations (179) and (180)).146... 

Several stoichiometric methods for transition metal-promoted transformations of allenes have been studied, involving metals such as iron [77] and titanium [78, 79]. The titanium-mediated reactions developed by Sato and co-workers have probably the greatest synthetic impact, as exemplified by the conversion of silylated allene 150 to 1,4-diene 152 (Scheme 14.38) [78],... 

W. Liu, and M. Flytzani-Stephanopoulos, Transition metal-promoted oxidation catalysis by fluorite oxides A study of CO oxidation over Cu—Ce02, Chem. Eng. J. 64, 283—294 (1996). 

Balme G, Bouyssi D, Monteiro N (2006) The Virtue of Michael-Type Addition Processes in the Design of Transition Metal-Promoted Cyclizative Cascade Reactions. 19 115-148 Barluenga J, Rodriguez F, Fanands FJ, Fldrez J (2004) Cycloaddition Reaction of Group 6 Fischer Carbene Complexes. 23 59-121 Basset J-M, see Candy J-P (2005) 16 151-210... 

Transition-metal-promoted cycloaddition is of much interest as a powerful tool for synthesis of carbocyclic stmcture in a single step. Utilization of carbon monoxide as a component of the cycloaddition reaction is now widely known as the Pauson-Khand reaction, which results in cyclopentenone formation starting from an alkyne, an alkene, and carbon monoxide mediated by cobalt catalyst. Although mechanistic understanding is limited, a commonly accepted mechanism is shown in Scheme 4.16. Formation of dicobalt-alkyne complex followed by alkene... 

Transition Metal Promoted Ring Expansion of Alkynyl- and Propadienylcyclopropanes... 

Contrary to the well-established chemistry of the vinylcyclopropanes, the corresponding reactions of alkynyl- and propadienylcyclopropanes have not, until recently, received much attention. We present here a summary of the recent efforts towards the development of transition metal promoted transformation of these molecules with a brief survey of the corresponding thermal reactions. 

The first catalyst systems were Cu promoted by phosphoric acid and then first row transition metals promoted by iodide. By the 1950s, the related reaction of carbonylation of MeOAc to AC2O was also known (Eq. (2)). 

Transition metal carbide catalysts have also been explored as methane partial oxidation catalysts [110] promising results were obtained over M02C systems and enhancements were reported with the addition of transition metal promoters. 

Transition metal-promoted allylzincation of disubstituted alkynes. . 901... 

Transition metal complexes with mercury directly bound to one or two transition metal centers are well known.1 They have found use as relatively air-stable sources of carbonyl metallate anions in polar solvents and as intermediates in the syntheses of bimetallic transition metal complexes. They are probably the key intermediates in the many transition metal promoted... 

M-butane proceeds via an intermolecular mechanism with 2-butene involved intermediately.300-303 The role of the transition metal promoters such as Fe and Mn was shown to increase the surface concentration of the intermediate butene 304 The formation of butene is speculated to occur through an oxidative dehydrogenation on the metal site305 or by one-electron oxidation.306... 

While there are differences in mechanistic detail, studies by others (13, 25) substantiate the existence of allylic hydroperoxides as intermediates in the homogeneous, transition-metal promoted oxidation of cyclohexene. 

Main Croup Element- and Transition Metal-Promoted Carboxylation of Organic Substrates (Alkanes, Alkenes, Alkynes, Aromatics, and Others)... 

Main Croup Element- and Transition Metal-Promoted Carboxylation 5.2... 

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