From Benzenoid Derivatives by Displacement of Nitro,Chloro and other Groups

3 From Benzenoid Derivatives by Displacement of nitro, chloro and other groups 

Nitro compounds activated by 2- or 4-groups such as nitro, cyano or alkoxycarbonyl, smoothly form ether derivatives by intermolecular or intramolecular pathways. 

The reaction of nucleophiles with chloroarene-Mn(CO)3 and fluoro arene-Cr(CO)3 complexes has been employed for the synthesis of diaryl ethers and has been particularly applied (ref. 55) to the selective arylation of polyfunctional phenols by reaction of the phenoxide formed from NaH in dimethylformamide with the 4-chlorotoluene-manganese tricarbonyl cation (as the hexafluorophosphate) in acetonitrile at ambient temperature over 18 hours. 

By contrast with the first example, the nitro group can sometimes be expelled. Thus, methyl 3-chloro-2-nitrobenzoate and the monopotassium salt of methyl 

5-dihydroxybenzoate (1.5 moles) in refluxing dimethylformamide containing cupric oxide gave the diphenyl ether shown in 60% yield (ref.56) with displacement of the nitrite ion. 

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