Arenes from Grignard reagents

In equation 1, the Grignard reagent, C H MgBr, plays a dual role as reducing agent and the source of the arene compound (see Grignard reaction). The Cr(CO)g is recovered from an apparent phenyl chromium intermediate by the addition of water (19,20). Other routes to chromium hexacarbonyl are possible, and an excellent summary of chromium carbonyl and derivatives can be found in reference 2. The only access to the less stable Cr(—II) and Cr(—I) oxidation states is by reduction of Cr(CO)g. 

All attempts to combine sterically overcrowded alkyl Grignard reagents of the neopenthyl type with the spiroarsonium skeleton 120 led directly to the rearranged structures 126. It is not clear whether these reactions involve the corresponding arsoranes 122i, j as short lived intermediates or whether the nucleophilic attack is directed here from the beginning toward an arene ligand123). 

E)-l-Chloro-3-(N,N-dimethylamino)-1-arylprop-l-enes are conveniently prepared from aryl chloropropeniminium salts by reduction with sodium cyanoborohydride.75 Those iminium salts also undergo 1,2-addition of Grignard reagents (Scheme 32). N,N-Dialkylaminomethyl arenes can be obtained by the reaction of... 

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