Nuclear Chlorine, Bromine or Fluorine from a Phenolic Ether

Conversion of 4-tert-butoxychlorobenzene in tetrahydrofuran to the Grignard reagent and reaction with vinyl chloride in the presence of a small proportion of dichloro[1,3-bis(diphenylphosphino)propane]nickel at 30-40X over a total reaction time of 6.5 hours furnished 4-tert-butoxystyrene in 93% yield (ref. 138). 

The Grignard reagent prepared from 4-bromophenyl trifluoromethyl ether in diethyl ether, with trifluoroacetic anhydride gave 4-trifluoromethoxy-trifluoroacetophenone (ref. 139). 

2-Fluoroanisole or 3-fluoroanisole with an n-alkyllithium in 2-4 molar excess in dry ethereal solution followed by quenching of the reaction mixture by addition to solid carbon dioxide and subsequent acidification with dilute hydrochloric acid afford the 6-n-alkyl-2-methoxybenzoic acid in moderate yield through intermediate formation of 2-anisyne. By contrast, 4-fluoroanisole gives mainly 2-methoxy-5-fluorobenzoic acid (ref.140). 

The formation of 3,5-bis[(2-hydroxy-2-methyl)ethyl]anisole from 2,6-dibromo-anisole by way of a zirconocene intermediate has been reported (ref. 141). A pentane solution of n-butyllithium (4moles) was added to 1 mole of 

Displacement of bromide ion from 2-bromophenoxy(dimethyl)chloro-methylsilane with sodium in refluxing toluene, until monitoring indicated completion of reaction, occurred with formation of 2,3-dihydro-1,3-benzoxasilole in 60% yield (ref. 142). 

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