And ipso substitution

Heteroaromatic Sulfoxides and Sulfones Ligand Exchange and Coupling in Sulfuranes and Ipso-Substitutions... 

Nitroquinoxaline is reactive toward various nucleophiles and ipso substitution with oxygen, nitrogen and sulfur nucleophiles affords the corresponding 2-substituted derivatives. ... 

Heteroaromatic compounds, radical ipso attack and ipso substitution 8OACR51. 

Radical ipso attack and ipso substitution in aromatic compounds , Tiecco, M., Acc. Chem. Res., 1980, 13, 51. 

This shows a plot of the yield of each nitroproduct against % H2S0i and also incorporated is an indication of total yield of nitroproducts recovered. All data are based on the initial quantity of aromatic compound. Quantitative yields of the nitroproducts are obtained above about 70% H2SO1, and the drop in yield and in the amount of 3-substitution below that acidity can be attributed to nucleophilic capture of the ipso -substituted Wheland intermediate. The change in amount of 4-substitution is however much less than the corresponding change for o -xylene. For o-diethylbenzene the combination of 3-and ipso-substitution is less at all acidities presumably for steric reasons. o-Xylene then behaves in a way, even when ipso - substitution is allowed for, that would be unsuspected from a study of toluene or oj-diethylbenzene. 

Reactions of 2-trialkylsilyl- and trialkylstannyl-substituted furans with benzhydryl cations provided 2,5-disubstituted furans and ipso-substituted furans. Kinetic investigations of the reactions revealed that the monosubstituted product was produced from the protonolysis of the 2,5-disubstituted furylstannane, while the 2,5-disubstituted furan was derived from an electrophilic substitution of the mono-substituted furan. Introduction of a trialkylsilyl and a trialkylstannyl group to the 2-position of furan hardly affected the reactivity of this position towards carbenium ions ipso attack), while the 5-position is somewhat activated <01OL1629,01OL1633>. 

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