Cycloheptatriene, reaction+carbonyls

Morita and coworkers [76] described a [8+2] cycloaddition of 8-oxoheptafulvene 299, a heptafulvene ketene, with cycloheptatriene iron carbonyl 300 to give tricyclo[8.5.0.0 ]pentadeca-3,5,7,ll,13-pentaene-2-one Fe(CO)3 301 (Scheme 7.66). Usually, ketenes undergo [2+2] cycloaddition reactions (see above), and the observation mentioned here is a special case. 

The carbonyl undergoes a variety of complex formation reactions, involving partial or total replacement of CO groups with other donors. Many reactions have synthetic applications. Such donors include pyridine (py), diglyme, toluene, aniline, cycloheptatriene, alkyl disulfide and metal cyctopentadiene. A few examples are given below ... 

Some interesting reactions have recently been found to occur on heating cycloheptatriene with some organosiliconruthenium carbonyls. An unexpected feature of these reactions is the migration of trimethyl-silyl groups from the metal to the 7r-ligand (R = Me) (17, 74) ... 

In the course of a study of the formation of fluorophosphoranes from chloro-phosphines (22) we observed one exception in the compound chloromethyldi-chlorophosphine, which reacted smoothly with antimony trifluoride to give the flammable fluorophosphine, C1CH2PF2, under conditions where many other chloro-phosphines were invariably converted into fluorophosphoranes. As this fluorophosphine is readily available, its interaction with a metal carbonyl derivative was studied, and cycloheptatriene molybdenum tricarbonyl, obtained from the reaction of molybdenum hexacarbonyl with cycloheptatriene (I, 2), was chosen as a starting compound. 

Formation of 648 from 647 was experimentally discarded. Since the most basic site of 646 is the carbonyl group, both Bronsted and Lewis acids should first coordinate to this position. In the case of Bronsted acid, protonation could occur at the electron-rich 9-position, and this was followed by deprotonation at the 1 la-position, which is promoted by the carbonyl protonation. In contrast, the Lewis acid cannot add to the 9-position and thus the skeletal rearrangement to give 648 took place. This kind of rearrangement through norcaradiene tautomers, shown in Scheme 128, is called walk rearrangement in thermal reaction of cycloheptatrienes <2002CL260>. 

Diene)Mn(CO)3 anions are stable in solution, and have been characterized by infrared and NMR spectroscopy. However, exposure of the anion solution to oxygen results in decomposition to give the free ligand. Reduction of (crotyl)Mn(CO)4 (62) gives the manganese-carbonyl transfer reagent ( -2-butene)Mn(CO)4. Reaction of 1,3-cycloheptadiene, 1,3-cyclooctadiene, 1,3,5-cycloheptatriene or 1,3,5,7-cyclooctatetraene... 

The seven-membered cyclic ketone, tropone, C7H7O, might be expected to form complexes like those of cycloheptatriene. Only the iron carbonyl complexes have been studied in any detail. Troponeiron tricarbonyl is one of the products of the reaction between acetylene and Fe2(CO)9 131a) this reaction, and the properties of the complex, have been summarized by Pettit and Emerson (118). Reaction betvreen Fc3(CO)i2 and phenylacetylene gives two isomeric complexes of formula (2,4,6-triphenyltropone)Fe(CO)3, which are assigned structures (VIII) and (IX) IS). 

Since Theodor Curtius reported the synthesis of ethyl diazoacetate in 1883, Buchner had investigated its reactions with carbonyl compounds, alkenes, alkynes, and aromatic compounds for more than 30 years.His extensive contributions in this area resulted in two reactions named in his honor the Buchner-Curtius-Schlotterbeck reaction (formation of ketones from aldehydes and aliphatic diazo compounds) and the Buchner reaction. The prototypical example of the latter involves the thermal or photochemical reaction of ethyl diazoacetate with benzene to give (via norcaradiene 7) a mixture of four isomeric cycloheptatrienes 8-11. Initially, Buchner believed that a single norcaradiene product 7 was generated from this reaction, but later, he realized that the hydrolysis of the product afforded a mixture of four isomeric carboxylix acids. The norcaradiene formulation persisted until 1956 when Doering reinvestigated this reaction. ... 

The stability of arene carbonyls toward an exchange reaction, equation (6-60), is given by benzene < toluene < cycloheptatriene naphthalene. 

The photoreactions of cyclopolyene metal carbonyls have become useful routes for the synthesis of oligocyclic adducts. The use of photochemical reactions has the advantage over thermal reactions for these conversions in that the desired products can often be obtained in high selectivity. One of the earliest examples of such a reaction is the photoaddition of butadiene to Cr(CO)3( 7-1,3,5-cycloheptatriene) to give Cr(CO)3(i/-bicyclo[4.4.1]undeca-l,3,7-triene) (Ref. 132) ... 

Several metal carbonyls are known to react with l,3,S-cycloheptatriene to give metal complexes in which carbonyl groups have been displaced by three olehnic bonds and it seems possible that an analogous reaction might... 

The irradiation of methyl phenylglyoxylate, benzil, benzophenone, and 1,4-benzoquinone in the presence of homobenzvalene 103 gave, as products of the Paternb-Biichi reaction, oxetane derivatives that contain the tricyclo[4.1.0.0 > ]heptane subunit as well as ring-opened products. In the case of benzophenone, the cycloaddition competes with the isomerization of 103 to cycloheptatriene. Exclusive isomerization was observed with acetophenone and acetone. Carbonyl compounds with triplet energies lower than 69 kcal/mol prefer the cycloaddition path. Cyclopent-2-en-l-one is an exception to this rule in spite of its triplet energy of 74 kcal/mol, [2-l-2]-cycloadducts were formed rather efficiently. 

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