| Abstract
| - Evidence for the intermediacy of a vinyl radical in the vinylicSRN1 reaction (SRN1(V)) of2-anisyl-1,2-diphenylvinyl bromide 2 is obtained. Thephotostimulated SRN1(V) reaction of pinacoloneenolateion with (E)-2 and (Z)-2,which are used as stereoindicators, gives complete loss of theoriginalstereochemistry of the two precursors in the substituted andhydrodehalogenated products; i.e.,stereoconvergence is found. It is concluded that in the reactionof 2 a β-substituted α-phenylvinylradical is a reactive intermediate and that it has either a linearstructure or an average linearstructure due to a rapidly interconverting E,Zmixture of bent radicals. This conclusion issupportedby comparing the stereochemical course of the SRN1(V)reaction with those of other reactions of thesame precursor, which unambiguously give rise to the sameα-phenylvinyl radical intermediate byalternative mechanisms. Among the reactions investigated, thehydrodehalogenation of precursor2 by LAH appears to take place by an ETmechanism.
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