Grignard reagents aromatic nucleophilic substitution

Apart from nucleophilic substitution reactions, the chemistry of the halo derivatives of the 7r-deficient heterocycles is fairly similar to that of aromatic halides. Thus, heterobiaryls can be prepared by the Ullman reaction, and Grignard reagents and organolithium compounds can be prepared, although in many instances, and especially with Grignard reagents,... 

Grignard reagent.80 Competition by nucleophilic aromatic substitution was not observed unless the only active position(s) was (were) substituted with a leaving group, as in the reaction of l-methoxy-2-nitro-naphthalene which gave 1 -alkyl-2-nitronaphthalenes in 73-95% yields.81 The use of Me3SiCH2MgCl (Peterson reagent) provides an entry to nitro-substituted benzyl anion intermediates, as shown in the example of Scheme 9.82... 

In aromatic systems, oxazolines can have three different functions (Fig. 4). Firstly, they can be used as protecting groups for carboxylic acids. Secondly, they activate even electron-rich aromatic systems for nucleophilic substitution. Fluorine or alkoxy groups in the ortho position can be substituted by strong nucleophiles such as Grignard reagents. Thirdly, when biaryl compounds with axial chirality are synthesized in these reactions, oxazolines can induce the formation of only one atropisomer with excellent selectivity. These three qualities were all used in the synthesis of 20, a precursor of the natural product isochizandrine [10]. 

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