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.
A search for unambiguous vinylic SRN1 reactions / A., Annunziata; Galli, Carlo; Gentili, Patrizia; A., Guarnieri; M., BEIT YANNAI; Z., Rappoport. - In: EUROPEAN JOURNAL OF ORGANIC CHEMISTRY. - ISSN 1434-193X. - (2002), pp. 2136-2143. [10.1002/1099-0690(200207)]
A search for unambiguous vinylic SRN1 reactions
GALLI, Carlo;GENTILI, Patrizia;
2002
Abstract
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.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
