Insertion reactions carbonyl

Naphthaleneacetic acid has also been prepared by the carbonyl-insertion reaction of 1-chloromethylnaphthalene cataly2ed by carbonyl cobalt cation (90,91). Carboxylation of 1-chloromethylnaphthalene in the presence of the catalyst Pd[P(CgH )2]2Cl2 under phase-transfer conditions gave 1-naphthaleneacetic acid in 78% yield (92). 

Another important line of investigation concerned the carbonyl insertion reaction, which was best defined in manganese chemistry (75, 16) and extended to acylcobalt tetracarbonyls by Heck and Breslow. The insertion may be through three-membered ring formation or by nucleophilic attack of an alkyl group on a coordinated CO group. 

Evans, D.A., Hurst, K.M., Truesdale, L.K., and Takacs, J.M., The carbonyl insertion reactions of mixed tervalent phosphorus-organosilicon reagents, Tetrahedron Lett., 2495, 1977. 

A unique Pd-catalyzed carbonyl insertion reaction of 197 furnished pyrido[2,l-b]quinazoline 198, an antiallergy agent [158]. This particular outcome may be substrate-specific. 

The overall enthalpy change of the insertion process contains contributions from four bonds (M-CO, M-COR, M-R and CO-R). As there is no significant difference between (Mn-R) and Zs(Mn-COR) then, at least in the case of manganese and hydrocarbon groups, R, the dominant factor will be the difference between T (Mn-CO) and E R-COX) [for R = CH3, E = 339 kJ mop1 (X = H), 370 kJ mol"1 (X = Cl) (Ref.23 )] which suggests that the insertion reaction is thermodynamically favoured with respect to decarbonylation. Kinetic studies of the carbonyl insertion reaction in solution have shown87) that the enthalpy of activation is 62 kj mol-1 for inser-... 

Metal Hydrides. It is likely that the reduction of aldehydes to alcohols by cobalt hydrocarbonyl (27) is an example of a carbonyl insertion reaction with a metal hydride. It is not clear which way the hydrocarbonyl adds to the carbonyl groups —whether it forms a cobalt-carbon bond (2), or a cobalt-oxygen bond (90). 

Perhaps the most significant reaction of this class to be discovered and characterized is the carbonyl insertion reaction (Equation 10) (15). As indicated, the methyl group (or other sigma-bonded organic group) is converted into an... 

Reaction of the dianion [Ru6C(CO)16]2 4 with methyl iodide at 120°C affords the anionic duster [Ru6C(CO)i6(Me)J 73 in 40% yield.53 Cluster 73 undergoes a carbonyl insertion reaction under 50 atmospheres of CO to afford [Ru6C(CO)i6(COMe)] 74 in 56% yield (Scheme 14). The structures of 73 and 74 have been established by single crystal X-ray diffraction, which shows that the methyl group in 73 bonds to an apical Ru atom and does not change location on carbonylation. 

Although bis(phosphite) carbyne complex Cp[P(OMe),]2Mo=C(c-Pr) is incapable of undergoing carbonyl insertion reactions, it adds 1 equivalent of HCl in ether forming the ring-opened -butadiene complex Cp[P(OMe),l(Cl)Mo( 4-butadiene) in 15% yield, and P(OMe)j in equal amounts (equation 108)158. Careful analysis of the reaction using... 

Fyfe et al. (354) have combined 31P and 13C CP/MAS NMR studies first to identify the polymer-immobilized catalyst (Scheme 4, compound ii) formed from the precursor i by treatment with Pd(PPh3)4 and, second, to monitor the carbonyl insertion reaction using 13C-enriched CO to yield iii. The use of isotopically enriched CO was required so as to record meaningful signals above those emerging from the carbon-rich polymer background. 

The following discussion deals not only with this reaction, but related reactions in which a transition metal complex achieves the addition of carbon monoxide to an alkene or alkyne to yield carboxylic acids and their derivatives. These reactions take place either by the insertion of an alkene (or alkyne) into a metal-hydride bond (equation 1) or into a metal-carboxylate bond (equation 2) as the initial key step. Subsequent steps include carbonyl insertion reactions, metal-acyl hydrogenolysis or solvolysis and metal-carbon bond protonolysis. 

Carbonyl insertion reactions, general considerations, 1, 105 Carbonyl ligands... 

The great reluctance of silicon-metal compounds to undergo carbonyl insertion reactions, familiar in analogous C-metal chemistry, is discussed in Section III,B. Entry 43 shows the reverse process a sila-acyl derivative (XIII), prepared by the reaction (14) of Eq. (48),... 

Other metallacyclobutane derivatives demonstrate similar two-atom carbonyl insertion reactions, as previously reviewed in CHEC-II(1996) <1996CHEC-II(lb)887>. The insertion of diphenylketene occurs exclusively into the C(sp3)-Ti bond of a-methylenetitanacyclobutane complex 79 to give oxatitanacyclohexane 101 (Equation 31) <1993JOM181>. In contrast, no reaction was observed using carbon dioxide or arylisocyanate at room temperature (see Section 2.12.6.2.4). 

The mechanisms of the two key steps are worth discussion. Hydrometallation occurs by initial n-complex formation followed by addition of the metal to one end of the alkene and hydrogen to the other. Both of these regioisomers are formed. The carbonyl insertion reaction is another migration from the metal to the carbon atom of a CO ligand. 

Although bis(phosphite) carbyne complex Cp[P(OMe)3]2Mo=C(c-Pr) is incapable of undergoing carbonyl insertion reactions, it adds 1 equivalent of HCl in ether forming the ring-opened f/ -butadiene complex Cp[P(OMe)3](Cl)Mo( / -butadiene) in 15% yield, and P(OMe)3 in equal amounts (equation 108) . Careful analysis of the reaction using two equivalents of HCl reveals the presence of the metal hydride complex Cp[P(OMe)3]2Cl2MoH as the main products (70%), and free butadiene. It was furthermore shown that the two molybdenum complexes are not interconvertible under the reaction conditions and both the yields and products ratio are invariant with temperature in the range of -40 °C to room temperature and the amount of added HCl (1 or 2 equivalents). 

By the nature of its molecular mechanism, the carbonyl-insertion reaction represents a typical reaction mode of o alkyltransition metal complexes. Formation of the new C—C cr-bond takes place during a 1,2-alkyl-migration step, transforming an alkylmetal carbonyl moiety [cts-M(CO)R] into an acylmetal unit (M—COR) (89). In general, (s-cir-diene)-zirconocene complexes 5 appear to exhibit a substantial alkylmetal character (90). Therefore, it is not too surprising that some members of this class of compounds [in contrast to most other dienetransition metal complexes (97)] react with carbon monoxide with C—C bond formation (45). However, as demonstrated by X-ray structural data for 5 (Tables V... 

Surprisingly, the 2,3-epoxide ring of pyranoid or furanoid derivatives proved to be highly unreactive toward carbonyl insertion reactions or in rearrangement to ketoses, either when catalyzed by hydrogen cobalt tetracarbonyl or sodium cobalt tetracarbonyl. When moisture was not carefully excluded, preferential hydrolysis of the epoxide ring occurred to afford the diaxial product. 

Although methyl tri-0-acetyl-2-deoxy-2-iodo-/3-D-glucopyranoside failed to undergo a carbonyl-insertion reaction, it is interesting to... 

The result is that a reaction that initially appears to involve CO insertion, and is often so designated, does not involve CO insertion at all It is not uncommon, on close study, for reactions to differ substantially from how they might at first appear the carbonyl insertion reaction may in fact be more complicated than described here. In this reaction, as well as in all chemical reactions, it is extremely important for chemists to be willing to undertake mechanistic studies and to keep an open mind about possible... 

Monsanto acetic acid synthesis 4), and the hydroformylation or 0X0 reaction (5). A key mechanistic step in catalytic carbonylation reactions is the migration of an alkyl group onto an adjacent carbonyl ligand. This reaction involves the formation of a new carbon-carbon bond and has been termed a carbonyl insertion reaction since a CO ligand has been formally inserted into the transition metal-carbon (r-bond. Because of the industrial and commercial importance of these catalytic reactions, the search for stoichiometric systems in which this step can be observed directly has been, and still is, one of great endeavor. 

Classic examples of complexes showing the carbonyl insertion reaction are the complexes [Mn(R)(CO)5] (R = alkyl). Alkylpentacarbonyl complexes of the manganese group are also important from both fundamental and theoretical standpoints since they contain the alkyl group and CO in activated forms by virtue of coordination of the metai. 

I) Nickel, Palladium, and Platinum. For the elements of group VIII, an assessment of the relative reactivity for the carbonyl insertion reaction is available in the literature. For reaction (a), koss (x s , 2.3°C) of the process was found to decrease in the... 

Alkenyl substituents attached to aziridine ring carbons allow a palladium-catalyzed carbonyl-insertion reaction to occur, producing a /1-lactam (Scheme 46) <91SL91>. The proposed mechanism <93BMC2415> is based on an analogous reaction of vinyl epoxides <85JA6123>. Initial attack of palladium(O) on the optically active /ra .s-vinylaziridine (67) leads to the zr-allyl palladium complex... 

The formation of acyl complexes is an important step in carbonyl insertion reactions,23 as described in Chapter 8 (Section 8-1-1). 

Attempted formation of t/ -tricarbonylchromium(0) complexes of cyclopropa[/)]naphthalene (3) or l/f-cyclopropa[6]anthracene (7) by reaction of these ligands with tris(acetonitrilc)tricar-bonylchromium(O) resulted in the formation of the corresponding annulated cyclobutenone derivatives 6 and 8 in 57 and 54% yield, respectively, as the result of carbonyl-insertion reactions. 

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