Reagents as bases

The use of organomagnesium reagents as bases leads to complexation of the nitrile imines (e.g., 141), which has been found to have a strong effect in promoting syn selectivity in reactions with methyl 2-(l-hydroxyalkyl)acrylates via coordination of the metal atom with the alcoholic oxygen (e.g., leading to the formation of 142). Lithium complexation had little effect (78). 

W. Kosar, Grignard Reagents as Bases, in Handbook of Grignard Reagents (G. S. Silverman, P. E. Rakita, Eds.), Marcel Dekker Inc., New York, 1996, 441-454. 

Grignard reagents as bases alkyllithium reagents are not generally useful because of competing addition to the carbon-nitrogen double bond. Depending upon the experimental conditions e.g. solvent, temperature and base) and the nature of the N-substituent, deprotonation of the unsymmetrical ketimines (2 =... 

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