Substitution of carbon monoxide

Substitution of carbon monoxide by phosphines has been observed for bis(dimethylgermylethane-iron tetracarbonyl <890M1585>. 

In this chapter, the recent advances in amidocarbonylations, cyclohydrocarbonylations, aminocarbonylations, cascade carbonylative cyclizations, carbonylative ring-expansion reactions, thiocarbonylations, and related reactions are reviewed and the scope and mechanisms of these reactions are discussed. It is clear that these carbonylation reactions play important roles in synthetic organic chemistry as well as organometallic chemistry. Some of the reactions have already been used in industrial processes and many others have high potential to become commercial processes in the future. The use of microwave irradiation and substitutes of carbon monoxide has made carbonylation processes suitable for combinatorial chemistry and laboratory syntheses without using carbon monoxide gas. The use of non-conventional reaction media such as SCCO2 and ionic liquids makes product separation and catalyst recovery/reuse easier. Thus, these processes can be operated in an environmentally friendly manner. Judging from the innovative developments in various carbonylations in the last decade, it is easy to anticipate that newer and creative advances will be made in the next decade in carbonylation reactions and processes. 

Exchange and Substitution of Carbon Monoxide in Carbonyl and Substituted Carbonyl Complexes 288... 

For this compound, which is closely related to the isoelectronic Hg[Fe(CO)3NO]2 (45) (Section IX) and to Hg[Mn(CO)5]2 (VII, 79), a convenient method of preparation in aqueous solution was discovered in conjunction with E. O. Fischer (46). Moreover, we could make IIg[Co(CO)4]2 react, like Co2(CO)8, with ligands either with substitution of carbon monoxide and formation of Hg[Co(CO)3L]2 (L = PR3, AsR3, SbR3), or by valence disproportionation of cobalt (VII, 80) using nitrogen bases or isonitriles, e.g.,... 

With C6H5PF2, the substitution of carbon monoxide was complete 162), On the contrary, P(CF3)3 70) and P[N(CH3)]2C1 I48) gave only mono- and disubstitution. 

Substitution of carbon monoxide ligands by one acetylene is the first step in the reaction of alkynes with metal carbonyk. This is well-established in the case of cobalt carbonyls by the isolation of substitution-type complexes of formula RC R Co CCO) (1) and RC2R Co (CO)j (2). Three different types of alkyne-substituted iron carbonyls have been isolated from iron carbonyls particularly with acetylenes having bulky substituents (3). They have recently been shown to be intermediates in the formation of complexes with more complicated organic ligands as well as of cyclic organic products. 

Group VII. The rate law for reaction of PhaM—Mn(C0)6, where M = Si, Ge, or Sn, with a variety of nitrogen and phosphorus bases, both unidentate (e.g. phosphines) and bidentate (e.g. diphos, bipy), indicates parallel dissociative and associative mechanisms in all cases. This assignment of mechanisms on the basis of the rate law is supported by activation entropies determined for the respective terms. Exceptionally, the reaction of PhaSi—Mn(CO)s with trialkyl phosphites does not result in simple substitution of carbon monoxide by the phosphite, but produces trans-Mn(COR)(CO)s[P(OR)3]2 by way of a Michaelis-Arbuzov reaction. ... 

In order to achieve high yields, the reaction usually is conducted by application of high pressure. For laboratory use, the need for high-pressure equipment, together with the toxicity of carbon monoxide, makes that reaction less practicable. The scope of that reaction is limited to benzene, alkyl substituted and certain other electron-rich aromatic compounds. With mono-substituted benzenes, thepara-for-mylated product is formed preferentially. Super-acidic catalysts have been developed, for example generated from trifluoromethanesulfonic acid, hydrogen fluoride and boron trifluoride the application of elevated pressure is then not necessary. 

Another route to enantiomcrically pure iron-acyl complexes depends on a resolution of diastereomeric substituted iron-alkyl complexes16,17. Reaction of enantiomerically pure chloromethyl menthyl ether (6) with the anion of 5 provides the menthyloxymethyl complex 7. Photolysis of 7 in the presence of triphenylphosphane induces migratory insertion of carbon monoxide to provide a racemic mixture of the diastereomeric phosphane-substituted menthyloxymethyl complexes (-)-(/ )-8 and ( + )-( )-8 which are resolved by fractional crystallization. Treatment of either diastereomer (—)-(/J)-8 or ( I )-(.V)-8 with gaseous hydrogen chloride (see also Houben-Weyl, Vol 13/9a, p437) affords the enantiomeric chloromethyl complexes (-)-(R)-9 or (+ )-(S)-9 without epimerization of the iron center. 

The simplest primary alkyl cations, CHJ and C2H, are formed from methane and ethane, respectively, by SbPs—PHSO3 (Olah and Schlosberg, 1968 Olah et al., 1969) and by SbPs (Lukas and Kramer, 1971). In these cases, intermolecular electrophilic substitution of these ions at the precursor alkanes leads to oligocondensation products, e.g. tertiary butyl and hexyl ions. In the presence of carbon monoxide it has been found possible to intercept the intermediate CHJ and C2H quantitatively as oxocarbonium ions (Hogeveen et al., 1969 Hogeveen and Roobeek, 1972). The competition between the reactions of the ethyl cation with ethane and carbon monoxide, respectively, is illustrated by the following equations ... 

While the replacement of carbon monoxide by a tertiary phosphine ligand represents one of the most fundamental substitution reactions in metal carbonyl chemistry, it was not until 1975, some 16 years after the... 

High ligand concentrations and/or low partial pressures of carbon monoxide cause a predominance of species substituted by more than one phosphorus ligand. These species containing multiple ligands present a greater sterically hindered environment for the olefin substrate and favor the linear product (24). Trialkylphosphines, the more basic ligands of the... 

A three-component coumarin synthesis involves the Pd-catalysed coupling of o-iodophenols with alkynes and subsequent insertion of carbon monoxide. With internal alkynes, pyridine is the crucial base for successful annulation the regioselectivity with unsymmetrically substituted alkynes is only moderate (Scheme 43) . 

The synthetic approach to the benzo[fo]furan is similar to that of the thiophenes described in Scheme 39. The synthetic approach was described by Flynn et al. [73], and an example synthesis is given in Scheme 40. The appropriate iodophenol 104 is coupled to the aryl alkyne 111. The intermediate 155 is subsequently cyclized in the presence of an appropriately substituted aryl iodide, e.g., 107 under an atmosphere of carbon monoxide gas, to give the benzo[fr]furan chalcone derivative 156. Deprotection of the hydroxyl produces the target compound 157. 

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