Reduction unconjugated unsaturated

Unconjugated unsaturated aldehydes and ketones can be reduced without affecting the carbonyl group, particularly with a Pd catalyst Ni and Pt have been used, but the reduction must be terminated after the addition of 1 equiv. of hydrogen. The nitrile group also can survive the reduction of carbon-carbon unsaturation in the same molecule. 

Isophorone usually contains 2—5% of the isomer P-isophorone [471-01-2] (3,5,5-trimethyl-3-cyclohexen-l-one). The term a-isophorone is sometimes used ia referring to the a,P-unsaturated ketone, whereas P-isophorone connotes the unconjugated derivative. P-lsophorone (bp 186°C) is lower boiling than isophorone and can be converted to isophorone by distilling at reduced pressure ia the presence of -toluenesulfonic acid (188). Isophorone can be converted to P-isophorone by treatment with adipic acid (189) or H on(Ill) acetylacetoate (190). P-lsophorone can also be prepared from 4-bromoisophorone by reduction with chromous acetate (191). P-lsophorone can be used as an iatermediate ia the synthesis of carotenoids (192). 

Concerning chemical selectivities in multiple unsaturated acetylenic compounds, conjugated enynes are reduced with modest selectivity. The most difficult case involves the selective reduction of an enyne with a terminal double bond and an internal triple bond, because the difference in the rates of their hydrogenation is minimal. The hydrogenation of nonterminal, unconjugated diynes to (Z,Z)-dienes can be achieved in good yield. 

The hydride reduction of a,j8-unsaturated carbonyl compounds can take one of two courses. Initial reaction at the carbonyl group gives allylic alcohols. Usually, no further reduction takes place, since the unconjugated carbon-carbon double bond is inert to nucleophilic species. If initial attack is at the double bond, an enolate is produced. In protic solvents, this can lead to the carbonyl compounds, which can, in turn, be reduced, resulting ultimately in the saturated alcohol. For this reason, it is... 

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