Molybdenum carbonyls reactions

Molybdenum, tris(phenylenedithio)-structure, 1,63 Molybdenum alkoxides physical properties, 2,346 synthesis, 2,339 Molybdenum blue liquid-liquid extraction, 1,548 Molybdenum cofactor, 6,657 Molybdenum complexes acrylonitrile, 2,263 alkoxides, 3,1307 alkoxy carbonyl reactions, 2,355 alkyl, 3,1307 alkyl alkoxy reactions, 2,358 alkyl peroxides oxidation catalyses, 6,342 allyl, 3,1306... 

The presence of a 2-substitutent in 3-phenylazirines (17, R —H in Scheme 21) modifies the mode of reaction with molybdenum carbonyl.47 In contrast to pyrazine formation for (17, R =H see Section V,C,2), the alkenyl azirine (18, Scheme 22) is transformed in excellent yield into 2-phenyl-5-carboxy-methylpyrrole. This product probably arises by intramolecular cyclization within an intermediate dienylnitrene intermediate, and related reactions have been devised to synthesize isoxazoles (see Section IV,E,2) and pyrazoles (see Section IV,D,1).47 The molybdenum carbonyl-promoted formation of 2,5-disubstituted pyrroles47 has analogy in uncatalyzed thermal, but not photochemical decomposition of 3-phenyl-2//-azirine 2-acrylate.49... 

Scheme 6.47 Palladium-catalyzed carbonylation reactions yielding acids, esters, and lactones using molybdenum hexacarbonyl as a solid source of carbon monoxide.

In a similar manner, Jt-allyl complexes of manganese, iron, and molybdenum carbonyls have been obtained from the corresponding metal carbonyl halides [5], In the case of the reaction of dicarbonyl(r 5-cyclopentadienyl)molybdenum bromide with allyl bromide, the c-allyl derivative is obtained in 75% yield in dichloromethane, but the Jt-allyl complex is the sole product (95%), when the reaction is conducted in a watenbenzene two-phase system. Similar solvent effects are observed in the corresponding reaction of the iron compound. As with the cobalt tetracarbonyl anion, it is... 

Analogous carbonylation reactions using nickel and iron carbonyl based systems also produce alkanecarboxylic acids [11, 13, 14]. The mechanism of the conversion of benzyl halides into arylacetic acids using iron pentacarbonyl is not as well defined as it is for reactions promoted by nickel or molybdenum carbonyl complexes. Iron... 

When sodium ethoxide is used in place of sodium hydroxide in the carbonylation reaction of benzyl halides with dicobalt octacarbonyl, ethyl esters are produced instead of the acids [15], Esters are also produced directly from iodoalkanes through their reaction with molybdenum hexacarbonyl in the presence of tetra-/i-butylammo-nium fluoride [16]. Di-iodoalkanes produce lactones [16]. The reaction can be made catalytic in the hexacarbonyl by the addition of methyl formate [16]. t-Butyl arylacetic esters are produced in moderate yield (40-60%) under phase-transfer catalytic conditions in the palladium promoted carbonylation reaction with benzyl chlorides [17]. 

In addition to the successful reductive carbonylation systems utilizing the rhodium or palladium catalysts described above, a nonnoble metal system has been developed (27). When methyl acetate or dimethyl ether was treated with carbon monoxide and hydrogen in the presence of an iodide compound, a trivalent phosphorous or nitrogen promoter, and a nickel-molybdenum or nickel-tungsten catalyst, EDA was formed. The catalytst is generated in the reaction mixture by addition of appropriate metallic complexes, such as 5 1 combination of bis(triphenylphosphine)-nickel dicarbonyl to molybdenum carbonyl. These same catalyst systems have proven effective as a rhodium replacement in methyl acetate carbonylations (28). Though the rates of EDA formation are slower than with the noble metals, the major advantage is the relative inexpense of catalytic materials. Chemistry virtually identical to noble-metal catalysis probably occurs since reaction profiles are very similar by products include acetic anhydride, acetaldehyde, and methane, with ethanol in trace quantities. 

Carbonylation of Dimethyl Ether and Methyl Acetate on Mo/A.C. Catalyst. In this section, the carbonylation of dimethyl ether and methyl acetate on Mo/A.C. catalyst was investigated. To our knowledge, molybdenum has never been reported to catalyze carbonylation reactions. 

Hi) Formation of transition metal carbonyl complexes Ashe and Colburn have reported (77JA8099) the synthesis of molybdenum carbonyl complexes of arsenin and antimonin but were unable to prepare bismin complexes because of its lability (Scheme 23). As expected for electron-rich aromatic compounds, both formed six-electron 7r-complexes (113) by a ligand displacement mechanism. Arsenin also forms a two-electron complex (114) analogous to those formed by pyridine, whereas antimonin did not give a similar complex under the conditions of this reaction. 

Support-bound transition metal complexes have mainly been prepared as insoluble catalysts. Table 4.1 lists representative examples of such polymer-bound complexes. Polystyrene-bound molybdenum carbonyl complexes have been prepared for the study of ligand substitution reactions and oxidative eliminations [51], Moreover, well-defined molybdenum, rhodium, and iridium phosphine complexes have been prepared on copolymers of PEG and silica [52]. Several reviews have covered the preparation and application of support-bound reagents, including transition metal complexes [53-59]. Examples of the preparation and uses of organomercury and organo-zinc compounds are discussed in Section 4.1. 

Iodine-Mercury(II) oxide, 149 Lithium diisopropylamide-Potassium /-butoxide, 164 Molybdenum carbonyl, 194 Phenyliodine(III) diacetate, 242 Sulfuryl chloride, 284 Conjugate addition reactions Michael reactions Alumina, 14... 

Scheme 2.29 depicts two of the first examples of microwave-assisted carbonylation reactions7. In these reactions, the temperature controls the rate of the CO release. Thus, during heating at 150°C in sealed vessels, carbon monoxide was smoothly emitted from the molybdenum carbonyl complex into the reaction mixture (Fig. 2.1, Profile A). As a result, aryl iodides and bromides underwent efficient amino carbonylation with non-hindered, aliphatic, primary and secondary amines in only 15 min, using Herrmann s palladacycle as pre-catalyst7 (Scheme 2.29). In contrast, at a reaction temperature of 210°C, carbon monoxide was liberated almost instantaneously (Fig. 2.1, Profile B).

Kaiser, N.F.K., Hallberg, A. and Larhed, M In situ generation of carbon monoxide from solid molybdenum hexacarbonyl a convenient and fast route to palladium-catalysed carbonylation reactions, J. Comb. Chem., 2002, 4, 109-111. 

Cyclic amino-carbenes, in molybdenum carbonyls, 5, 457 Cyclic bis(phosphine) dichlorides, with iron carbonyls, 6, 48 Cyclic carbenes, as gold atom ligands, 2, 289 Cyclic carbometallation, zirconium complexes, 10, 276 Cyclic carbozirconation characteristics, 10, 276 intermolecular reactions, 10, 278 intramolecular reactions, 10, 278 Cyclic dinuclear ylides, and gold , 2, 276 Cyclic 1,2-diols, intramolecular coupling to, 11, 51 Cyclic enones, diastereoselective cuprate additions, 9, 515 Cyclic esters, ring-opening polymerization, via lanthanide catalysis, 4, 145 Cyclic ethers... 

Cyclobutenes, in Pauson-Khand reaction, 11, 352 Cyclocarbonylation reactions, alkynes, 10, 714 Cyclo-C3 complexes, with molybdenum carbonyls, 5, 440 Cyclo-C4 complexes, in molybdenum carbonyls, 5, 448 Cyclochrome P450cam, aryldiazene reactions, 6, 107 Cyclodextrins... 

Dithiocarbamates, in Ru and Os half-sandwiches, 6, 493 Dithiocarbenes, Pt complexes, 8, 439 Dithiocarboxy ligands, in molybdenum carbonyls, 5, 447 Dithiolate-bridged compounds in dinuclear iron compounds with Fe-Fe bonds, 6, 238 as iron-only hydrogenase biomimetic models, 6, 239 Dithiolate diamides, with Zr(IV), 4, 784 Dithiolene—uranium complexes, synthesis and characterization, 4, 212 Ditopic receptors, characteristics, 12, 489 Ditungsten complexes, associated reactions, 5, 748 Divinyllead diacetates... 

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