Grignard reagents, bonding deprotonation

The regiochemistry of deprotonation of imines derived from unsymmetrical ketones is of special significance for the synthetic applications of these anions for carbon-carbon bond formation. This selectivity is sensitive to both the amine moiety and the base used. With imines derived from cyclohexyl- or r-butyl-amine, deprotonation with either Grignard reagents or lithium dialkylamide bases will result in high selectivity (>98 2) for removal of the proton on the less substituted a-carbon as in equations (39) and (40). 3i... 

Metallated imines can be formed from imines derived from enolizable carbonyl compounds by deprotonation with Grignard reagents or organolithium reagents, but more recent studies have generally involved the use of lithium dialkylamides, e.g. LDA, as the base. Alternative methods of producing metallated imines, e.g. addition of r-butyllithium to the imine double bond of 2-azadienes, are known. 

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 =... 

Reactions of different organometallic species with thiocarbonyi compounds have been extensively investigated and been shown to proceed both in a carbophilic and a thiophilic fashion. However, other reactions can be observed simultaneously such as reduction, double addition, coupling, deprotonation and formation of enesulfides1,226,423. A complex pattern appears in the reactions of thioketones with lithium or Grignard reagents424. The first application of Reformatsky reagents in C—C bond formation by reaction with... 

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