Osmium-promoted electrophilic substitution of anisoles: a versatile new method for the incorporation of carbon substituents

The coordination of the pentaammineosmium(II) metal center to different kinds of anisoles has been found to radically increase the nucleophilicity of the arene. Reactions occur with a large variety of carbon electrophiles in the presence of acidic acetonitrile at -40 degrees C to produce characterizable 4H-anisolium intermediates. Upon deprotonation and decomplexation, the 4-substituted anisole is returned in overall yields usually greater than 80 %.