Polar effects in free-radical reactions. New homolytic substitutions of heteroaromatic bases and quinones by ethyl vinyl ether and hydroperoxides

Trapping of t-butoxy radical by ethyl vinyl ether represents a strong evidence of the free-radical mechanism of the Gif reaction, in contrast with Barton's interpretation. The reaction has been developed from a synthetic point of view for new selective substitutions of heteroaromatic bases and quinones. The fundamental role of the polar effects in determining the selectivity is discussed.