Hydrogenolysis of Si-O Bonds

Lunzer, S., and Kramer, R., in press as indicated by Professor Kramer at the 4th Pannonian International Symposium on Catalysis, Smolenice, 1998. 

Bartok, M., (Ed.), Stereochemistry of Heterogeneous Metal Catalysis, Wiley, New York, 1985. 

Bartok, M., Torok, I., and Szabo, I., Acta Chim. Acad. Sci. Hung 76, 417 (1973). 

Marco-Contelles, J., Carmen Pozuelo, M. L., Martinez, L., and Martinez-Grau, A., J. Org. 

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Examples of the formylation of aryl halides with synthesis gas catalyzed by palladium complexes are summarized in Equation 19.90. These reactions relied upon the development of ligands with particular steric and electronic properties. The dia-damantyl-n-butyl phosphine shown in the equation, in combination with palladium acetate, leads to the formation of aromatic aldehydes in high yields from electron-rich and electron-poor aryl bromides. Reactions of nitroarenes and 2-bromopyridine provided the aldehydes in low yield, but other examples occurred in satisfactor) yield with only 0.1-0.75 mol % catalyst. The identity of the base is important in this process, and TMEDA was the most effective base. The mechanism of this process was not proposed in the initial work, but is likely to occur by oxidative addition of the aryl halide, insertion of the carbon monoxide into the palladium-aryl bond, and a combination of hydrogenolysis of the acyl intermediate and elimination of hydrogen halide to regenerate palladium(O). The base would then be involved in the hydrogenol5 sis and consumption of hydrogen halide. 

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