178100-44-2Relevant articles and documents
Kinetic stabilizing effect of the 4-N-methylacetamido substituent on the phenylnitrenium ion
Ruane, Patrick H.,McClelland, Robert A.
, p. 1875 - 1880 (2001)
Photolysis of 4-(N-methylacetamido)phenyl azide in aqueous solution results in quantitative formation of the 4-(N-methylacetamido)phenylnitrenium ion, this cation arising from solvent protonation of an initially formed singlet arylnitrene. The cation is observed by flash photolysis, and is identified through characteristic quenching by azide ion and by 2′-deoxyguanosine, both excellent nucleophiles for arylnitrenium ions in water. The nitrenium ion is protonated in acidic solutions to form the 4-(N-methylacetamido)aniline dication, whose pKa is determined to be 1.5 based on the rate-pH profile. This means that the nitrenium ion is relatively basic, which suggests that there is significant positive charge on the N-methylacetamido group. Further evidence for this is seen in the remarkably long lifetime (5 ms) of the nitrenium ion in water. In fact, the 4-(N-methylacetamido)phenylnitrenium ion is 5000-fold longer-lived than the 4-methoxy-substituted analog. A 4-methoxy substituent on a phenyl ring is more electron donating according to σ+ values (-0.78 for MeO vs. -0.60 for NMeAc). The dramatic reversal in the arylnitrenium ions is another example of the failure of these to follow the carbocation scale.
Thermolysis and radiofluorination of diaryliodonium salts derived from anilines
Linstad, Ethan J.,Vāvere, Amy L.,Hu, Bao,Kempinger, Jayson J.,Snyder, Scott E.,DiMagno, Stephen G.
supporting information, p. 2246 - 2252 (2017/03/17)
Aniline-derived diaryliodonium salts were synthesized and functionalized in good to excellent yields by judicious utilization of electron-withdrawing protecting groups. This simple approach opens another route to radiolabeling amino arenes in relatively complex molecules, such as flutemetamol.
