Cyclohexylamine Grignard reagent from

The overall sequence involves formation of the imine from the aldehyde that is to be alkylated— usually with a bulky primary amine such as t-butyl- or cyclohexylamine to discourage even further nucleophilic attack at the imine carbon. The imine is not usually isolated, but is deprotonated directly with LDA or a Grignard reagent (tl ese do not add to imines, but they will deprotonate them to give magnesium aza-enolates). 

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