ビニル炭素におけるS_N2反応 [in Japanese] Vinylic S_N2 Reaction [in Japanese]
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Vinylic nucleophilic substitution via a concerted bimolecular mechanism (S<SUB>N</SUB>V 2), which has long been rejected as a possible pathway, has recently been found to be feasible both theoretically and experimentally. Two S<SUB>N</SUB>V 2 mechanisms are possible : one is designated as S<SUB>N</SUB>Vσ where nucleophilic attack takes place in a molecular plane at the σ<SUP>*</SUP> orbital resulting in inversion of configuration, while the other as S<SUB>N</SUB>Vπ which involves out-of-plane π<SUP>*</SUP> attack of a nucleophile leading to stereochemical retention. Both modes of the concerted S<SUB>N</SUB>V 2 reactions were found for vinyl iodonium salts, and detailed mechanistic investigations are summarized. Intramolecular S<SUB>N</SUB>Vσ reactions were more often observed, and applied to some synthesis of cyclic compounds. Those observations are rationalized by high level ab initio MO calculations.
- J. Synth. Org. Chem. Jpn.
J. Synth. Org. Chem. Jpn. 64(4), 348-358, 2006-04-01
The Society of Synthetic Organic Chemistry, Japan