Organomagnesium compounds exchange with

Gilman s colour test 2, which depends on rapid metal-halogen exchange with 4-bromo-./V,7V-dimethylaniline, is positive for alkyllithium compounds [3], but not for organomagnesium compounds. 

Reactions of organomagnesium compounds with sulfoxides often result in ligand exchange [31], and may be complicated by a- or ortho metallation. However, in some cases, notably with 2-pyridyl aryl sulfoxides, reactions with arylmagnesium halides give useful yields of products from displacement of the aryl sulfoxido group [32, 33], e.g. [32]... 

Although in most cases reactions of organomagnesium compounds with sulfoxides give mixtures resulting from ligand exchange and/or deprotonation, examples have recently been described where... 

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