Addition of organomagnesium compounds to carbonyl groups

Although many of these reactions proceed in nearly quantitative yield, a few result in poor yields. Poor yields are most likely to be encountered in the synthesis of tertiary alcohols with bulky alkyl groups in which side reactions compete more effectively. The two most important side reactions are enohzation and reduction. Enolization can occur if the ketone has at least one hydrogen atom on either of the a-carbons and reduction can occur when the R of the Grignard reagent has hydrogen on its -carbon. 

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Addition of Organomagnesium Compounds to Carbonyl Groups, Pages 111-146... 

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