Unsaturated nitriles metal hydride

The olefinic bond of a,g-unsaturated carbonyl compounds can also be reduced by two transition metal hydrides, NaHFe2(CO)881 and NaHCr2(CO)10 82 Neither reagent reduces nitriles, ketones, aldehydes or non-conjugated carbon-carbon double bonds. 

Reduction of nitriles is an important method of preparing amines. It is, however, not always easy to carry out in spite of the unsaturated character of the nitrile group three methods are available (i) catalytic reduction, (ii) reduction by metal hydrides, and (iii) reduction by sodium in an alcohol. 

The synthesis of a,p-unsaturated carbonyl compounds and nitriles by Pd-catalyzed reaction [245] of allyl p-oxo esters and allyl a-cyano esters is an oxidative process. With the contra-polarizability of the metal ion, elimination of a hydride from the p-position is electronically favorable. 

The finely divided hydride makes it possible to prepare alcoholates of certain difunctional alcohols more readily than with sodium metal. Sodium reacts with the double bonds of conjugated unsaturated alcohols and reduces nitrile and carbonyl groups in difunctional group alcohols. With sodium hydride the alcoholates of these compounds can be formed. 

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