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Volume 72, 1981
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Diastereoselective control in ketose hydrogenations with supported copper and nickel catalysts

Abstract

A series of Cu and Ni catalysts has been studied in ketose hydrogenations. High diastereoselectivity to one of the two possible epimeric products occurs for each ketose in a series of pentulose and hexulose reactants. The preferred products of Cu catalysis fit a particular stereochemical trend and those from modified Ni systems the opposite trend, demonstrating control by the catalysts through 1,2-asymmetric induction.

In D-fructose reductions, the selectivity of Cu catalysts to D-mannitol can be increased by halide ions. The diastereoselectivity of Ni catalysts can be modified by sulphate doping from the D-mannitol selectivity of normal Ni systems to a high degree of control to D-glucitol. Although there is a definite trend in Ni catalysis, suggesting the involvement of hydrogen spillover, the selectivity in Cu systems is little influenced by change in support. In deuteration experiments, only one D-atom becomes attached to the carbon skeleton in the reduction steps.

The reasons for diastereoselectivity by 1,2-asymmetric induction are discussed in the light of these observations.

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Article information


Faraday Discuss. Chem. Soc., 1981,72, 397-411
Article type
Paper

Diastereoselective control in ketose hydrogenations with supported copper and nickel catalysts

J. F. Ruddlesden, A. Stewart, D. J. Thompson and R. Whelan, Faraday Discuss. Chem. Soc., 1981, 72, 397
DOI: 10.1039/DC9817200397

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