PhI(OTf)₂ Does Not Exist (Yet)*

Area of Science:

• Organic Chemistry
• Hypervalent Iodine Chemistry

Background:

• Phenyliodine(III) bis(trifluoromethanesulfonate) [PhI(OTf)2] has been widely utilized as a potent hypervalent iodine(III) oxidant in organic and inorganic synthesis for three decades.
• It is traditionally believed to be generated in situ via reactions involving phenyliodine(III) diacetate [PhI(OAc)2] or phenyliodine(III) oxide [PhI=O] with trimethylsilyl trifluoromethanesulfonate (TMS-OTf).

Purpose of the Study:

• To rigorously investigate the actual species formed under conditions previously attributed to PhI(OTf)2.
• To re-evaluate the mechanistic role of PhI(OTf)2 in established synthetic transformations.

Main Methods:

• Spectroscopic analysis (e.g., NMR, IR) of reaction mixtures generated under purported PhI(OTf)2 formation conditions.
• Computational chemistry calculations to support experimental observations and predict species stability.

Main Results:

• Spectroscopic data obtained from the in situ generation methods are inconsistent with the presence of PhI(OTf)2.
• Theoretical calculations corroborate the experimental findings, indicating that PhI(OTf)2 is not the actual species formed.

Conclusions:

• The commonly employed methods for generating PhI(OTf)2 in situ do not yield this specific hypervalent iodine(III) compound.
• The oxidizing capabilities previously ascribed to PhI(OTf)2 likely originate from other reactive species present in the reaction mixtures.
• Revisiting the mechanisms of reactions involving these generation methods is necessary.