Support ligand-promoted

Methanol carbonylation has been the subject of numerous reviews [6-17], including the seminal mechanistic studies by Denis Forster at Monsanto. This chapter does not seek to repeat all the information included in those reviews, but instead is focused on the important recent advances in process development and mechanistic understanding along with recent research efforts to identify new ligand-modified, supported, or promoted catalysts. The increasing use of computational methods to model catalytic mechanisms and potential alternative catalytic routes to acetic acid are also summarized. 

Ligand promoted dissolution of the AI2O3 support leads to the precipitation of... 

The NHC were chosen as supporting ligands as a result of comparisons with previously described catalytic systems based on dicationic phosphine or sterically encumbered P-diimine. The phosphine and p-diimine systems prevent chain transfer and termination processes. By analogy, it was speculated that mutually c/s-chelating NHC, stabilized by sterically demanding aryl substituents, would help promote the copolymerization of ethylene and carbon monoxide. Unfortunately, mesityl substituents on nitrogen atoms were the only... 

That depends upon the metal and supporting ligands used in the catalysis. For most palladium complexes, decarboxylation tends to occur however, a copper complex has been shown to promote the coupling instead of decarboxylation [99,100]... 

In terms of operational simplicity, one of the most significant advances entailed the use of copper catalysts for the synthesis of arylphosphonates. Many copper catalysts do not need to be stored in gloveboxes, and the common supporting ligands used for the solubilization of the copper sources tend to be air stable. A number of reports have detailed the use of copper catalysts to promote the formation of C—P bonds [394-395]. 

Cross-coupling chemistry has also been used to promote P—C bond-forming reactions between norbomadienyl triflates with secondary phosphines (Scheme 4.280) [444]. Palladium acetate was used as the palladium source in this reaction along with BINAP as the supporting ligand. The reaction conditions were mild (45 °C), and the authors oxidized... 

Gold catalysts containing NHC ligands can also promote cycloisomerisation reactions. Bicyclo[3.1.0]hexanes 137-139 can be prepared from the cycloisomerisation of 1,5-enynes bearing a propargyUc acetate (135) in the presence of catalytic amounts of [AuCl(lPr)]/AgBF (Scheme 5.36) [41]. The cycloisomerisation reaction of 135 occurs by a 1,3-OAc shift/aUene-ene cyclisation/l,2-OAc shift sequence. Experimental results with allenyl acetate 136 support this hypothesis as 139 is obtained in higher ratios than 137 and 138 [41b],... 

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