Reduction by Raney nickel

The transformations that use asymmetric heterogeneous catalysis will be highlighted P-keto esters and diketone reductions by Raney nickel catalyst modified with R,R-tartaric acid and NaBr. a-Keto acid reductions with cinchona modified Pt catalysts are discussed in Chapter 18. 

Epoxide cleavage, Sodium selenophenolate reacts with the furanose 1, prepared from D-glucose, to form the diselenide 3 in quantitative yield. This reaction involves formation and cleavage of the epoxide 2, which can be also prepared by treatment of 1 with NaH. The epoxide is cleaved regiospecifically by attack from the less hindered side at C4. The phenylseleno group can be removed reductively by Raney nickel. The product was used to prepare isoepiallomuscarine (5). 

O-r-Butyldimethylsilylnitroaldols show a peculiar reactivity with respect to the corresponding free vicinal nitro alcohols and play a central role in the synthesis of erythro- 1,2-amino alcohols (52). In fact, the diastereomeric enrichment of (51) can be preserved during reduction by Raney nickel. Thus, almost... 

Ar—C=C—N< (jS-nitrostyrenes,83 1-methylindoles84) however, bicyclic nitroalkenes are smoothly converted into the saturated amines by lithium aluminum hydride85 although their reduction by Raney nickel is incomplete salo, / -unsaturated cyanoacetic esters86 and occasional vinyl ketones87 can be reduced in good yield. 

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