Organomagnesien reactif reducteur

Prelog's rule, predicting the stereoselectivity of nucleophilic addition to the α-ketoesters of chiral alcohols, is also applicable to the reduction of α,β-ethylenic esters by LiAlH4, but this rule is no longer valid when organomagnesium halides are used as reducing agents. This difference between the two reactions is rationalized by the degree of complexation of the metallic ions of the two reducing agents in the transition states.