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A Search for Unambiguous Vinylic S RN 1 Reactions
Author(s) -
Annunziata Alfonso,
Galli Carlo,
Gentili Patrizia,
Guarnieri Alessandra,
BeitYannai Michal,
Rappoport Zvi
Publication year - 2002
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/1099-0690(200207)2002:13<2136::aid-ejoc2136>3.0.co;2-8
Subject(s) - chemistry , radical nucleophilic aromatic substitution , deprotonation , bromide , medicinal chemistry , nucleophile , ion , halide , nucleophilic substitution , stereochemistry , organic chemistry , nucleophilic aromatic substitution , catalysis
In a search for unambiguous examples of the vinylic S RN 1 route, vinyl bromides Ph(CH 3 )C=CHBr ( 10 ), Ph 2 C=CHBr ( 15 ), An 2 C=C(Br)An ( 18 ) and An 2 C=CBr 2 ( 20 ) were treated with Me 3 CCOCH 2 − under photostimulation conditions in Me 2 SO, whereas substrates PhCH=CHBr ( 2 ), Ph 2 C=C(Br)Ph ( 3 ), 10 and 15 were similarly allowed to react with PhS − and PhCH 2 S − . With the strongly basic enolate ion, the prevailing reactions were elimination/addition routes, α‐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 S RN 1 route with 2 , 3 and 15 . The nucleophilic character of the PhCH 2 S − 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. (© Wiley‐VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)