Substitution, nucleophilic internal

The allylmetallation of vinyl metals, y-heterosubstituted with a methoxy-methyl ether as the chelating group, leads to the corresponding gembismetal-lic derivatives,20 but now, warming the reaction mixture to room temperature promotes an internal nucleophilic substitution, leading to a metallated cyclopropane which can react with different electrophiles21 (Equation 7.5 and Protocol 9). 

The reaction between an alcohol and thionyl chloride proceeds via an internal nucleophilic substitution, SNi, in which retention is also observed at the substituted carbon. 

The replacement of an alcoholic hydroxyl group by a halogen atom is one of the most common reactions carried out in organic chemistry. The usual reagents for effecting the transformation include halogen acids, thionyl chloride, and phosphorus halides. The reaction is of particular theoretical interest since experiments with optically active alcohols suggest still another substitution process. It has been called an internal nucleophilic substitution reaction (S i).20... 

Rearrangement reactions, including internal nucleophilic substitution/displacement and skeletal rearrangement reactions. 

Clearly, the NEt2 group is involved. The nitrogen is a nucleophile and can do an internal nucleophilic substitution (S i), a very fast reaction for entropy reasons because two different molecules do not have to come together. 

On the other hand, when the two ligands are of sufficiently different polarity, the reaction is analogous to an internal nucleophilic substitution. The reaction will be mostly non-synchronous with a polar transition state. For this case, the abbreviation " LC " could be suggested. A large number of examples were discovered by Oae et al. in their extensive studies of the ligand coupling of sulfoxide... 

For the decarboxylation of arylfluoroformates, Christe and Pavlath suggest an internal nucleophilic substitution mechanism (Scheme 3). 

With this acetal, instead of hydrolyzing the intermediate benzyllithium, one can let it warm to room temperature, and an internal nucleophilic substitution takes place, whereby the acetal moiety behaves as a leaving group, and a trans-disubstituted cyclopropane is formed in 60-70% yield [39,41]. The first-formed stereogenic center remains unaffected in this second step, whereas the benzylic lithiated carbon is able to epimerize [38,39], leading to the more stable trans-cyclopropane [42-44] (Scheme 20). 

The only previously reported comparable case of temperature-dependent dissociation is an internal nucleophilic substitution from a covalent pentacoordinate to anionic pentacoordinate complex D. Schar, J. Belzner, in Organosilicon Chemistry 111, ed. N. Auner, J. Weis, VCH, Weinheim, 1997, p. 429. 

Benzoyl chlorosulfonate immediately rearranges into the acyl chloride (benzoyl chloride in our example) and SO2. This reaction is an interesting example of internal nucleophilic substitution. The internal nucleophile is the chlorine atom (it is electron-rich) which attacks the carbonyl carbon. The final products are benzoyl chloride and SO2. 

This conversion of 101 to 102 is a substitution, but the intermediacy of 104 leads to an intramolecular transfer of chlorine to displace sulfur dioxide. Reactions such as this are classified as internal nucleophilic substitution, which is abbreviated by the symbol SnI. 

Epoxides can be synthesized from internal nucleophilic substitution of halo-hydrins, which can be derived from hydrohalogenation of alkenes. 

The carbanion or ylide mechanism can be regarded as electrophilic migration to a negative centre analogous to the Wagner-Meerwein shift in carbonium ions ", but an equivalent and possibly more enlightening view is to consider the reaction as an internal nucleophilic substitution,. Ni (cf. 51) . Such mechanisms were once i considered operative in the decompositions of alkyl chlorosulphites, but although an ion-pair mechanism is now preferred for these processes ,... 

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