Oxazolines aryl, reaction with Grignard reagents

The procedure has also been applied to halobenzoic acids.3 Thus p-bromo-benzoic acid (6) was converted into the corresponding 2-oxazoline (7) as usual, and then into the Grignard derivative (8). This is, in effect, an aryl Grignard reagent with a protected carboxyl function. Reaction with an electrophile, for example benzonitrile, gives (9). The final step is hydrolysis. If carried out in 5-7% ethanolic sulfuric acid, the ester (10b) is obtained if carried out in an aqueous medium, the free acid (10a) is obtained. 

Fu et al. showed that a combination of NiCla and bis(oxazoline) 11 or 17 catalyses asymmetric Kumada coupling of racemic a-bromoketones with aryl Grignard reagents, giving a-arylketones in good yields and enantiomeric excess (Scheme 14.8). The reactions proceeded at low temperature, which enabled the asymmetric synthesis of racemisation-prone a-arylketones. The Pincer-nickel complex [(N2N)Ni-Cl] (18) catalyses Kumada reaction of primary allqrl bromides/iodides or secondary all l iodides with alkyl, (hetero)aryl or all nyl Grignard reagents (Scheme 14.9). The reactions... 

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