Reduction of Other Functional Groups

CHAPTER 5 REDUCTION OF CARBONYL AND OTHER FUNCTIONAL GROUPS 

5-hexenyl bromide and iodide gave mainly cyclic product. This result clearly 

The presence of transition metal ions has a catalytic effect on reduction of halides and tosylates by LiAlH4. Various copper hydrides, in particular, are effective for removal of halide and tosylate groups.  

Epoxides are converted to alcohols by L1A1H4. The reaction occurs by nucleophilic attack, which takes place preferentially at the less hindered carbon of the epoxide. Cyclohexene epoxides are preferentially reduced through transition 

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Reduction of Other Functional Groups by Hydride Donors... 

Magnesium oxide exhibited high activity and high selectivity in the hydrogen transfer from alcohols to studied nitroarenes. Because of the limited space of the paper the complete amine yield - temperature dependence was shown only for nitrobenzene reduction (Table 1). However, also for other reactants the yield of the aminic product increased continously between the values obtained at the lowest (350°C) and the highest (450°C) reaction temperatures. Below 350°C the complete lack of activity of MgO in the studied transformation was noted. The same was observed by us earlier (ref. 2) in the case the catalytic transfer reduction of other functional groups. 

Among the complexes which may function in this way are pentacyano-cobaltate ion, iron pentacarbonyl, the platinum-tin complex, and iridium and rhodium carbonyl phosphines. It has been suggested that with tristriphenylphosphine Rh(I) chloride, a dihydride is formed and that concerted addition of the two hydrogen atoms to the coordinated olefin occurs (16). There are few examples of the homogeneous reduction of other functional groups besides C=C, C=C, and C=C—C=C penta-cyanocobaltate incidentally is specific in reducing diolefins to monoolefins. 

Electrolytic methods have been applied for reduction of C—C multiple bonds more widely than is generally appreciated. Addition of hydrogen is often accompanied by simultaneous reduction of other functional groups, as when, / -unsaturated nitro compounds are converted into saturated amines 74 nevertheless, the method has also been recently used to convert unsaturated into saturated nitriles.75 Heterocyclic compounds can in many cases be converted into either partially or wholly saturated derivatives. For instance, 1,2,3,4-... 

Reduction of other functional groups. Certain thiones are reducible to afford chiral mercaptans. Using nitroaryl ketones " as substrates, the nitro group is preferentially reduced. 

Synthetic intermediates can be selectively deoxygenated without reduction of other functional groups such as esters, ketones, and oxime ethers (eq 3), as well as epoxides, acetate esters, and alkenes. ... 

As a general rule, the reduction of alcohols (R-OH) to hydrocarbons (R-H) cannot be achieved directly. Indeed, the catalytic reduction of other functional groups with hydrogen and metals such as platinum (Pt) or palladium (Pd) at or near room tem-... 

Reduction of other functional groups by hydride donors... 

In Section 15.9, we will consider reducing agents and their r ioselectivity. The reduction of carbonyl groups is sometimes accompanied by reduction of other functional groups. We will find that many synthetic variations are possible because several reducing agents with different reactivities and regioselectivities have been developed. 

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