A search for unambiguous vinylic SRN1 reactions

In a search for unambiguous examples of the vinylic S(RN)1 route, vinyl bromides Ph(CH3)C=CHBr (10), Ph2C=CHBr (15), An(2)C=C(Br)An (18) and An(2)C=CBr2 (20) were treated with Mc(3)CCOCH(2)(-) under photostimulation conditions in Me2SO, whereas substrates PhCH=CHBr (2), Ph2C=C(Br)Ph (3), 10 and 15 were similarly allowed to react with PhS- and PhCH2S-. With the strongly basic enolate ion, the prevailing reactions were elimination/addition routes, alpha-deprotonation followed by 1,2-Ph shift and bromide ion elimination, or halophilic steps. With 18, however, an S(RN)1 route was obtained. The weakly basic but reducing anion PhS- gave the SRN1 route with 2, 3 and 15. The nucleophilic character of the PhCH2S- anion instead prevailed with 15, whereas with 3 a variety of behaviours was obtained. The mechanistic interpretations were supported by the electrochemically determined redox potentials of the substrates