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Efficient and General One-Pot Synthesis of Diaryliodonium Triflates
tron-deficient salts are formed by the reaction of a General Procedure for Direct Synthesis of Salts 3
substituted aryl iodide with an arene. Alkyl-substitut- fromArenes and Iodine
ed iodonium salts can be formed via both routes in
m-Chloroperbenzoic acid (65% active oxidant, 3–4 equivs.,
similar yields. The protocol can be extended to the
see Table S5, Supporting Information) and iodine (30.0 mg,
synthesis of iodonium salts directly from iodine and
arenes, conveniently circumventing the need for aryl
iodides.
0.12 mmol) were dissolved in CH2Cl2 (1.0 mL) in a sealed
tube, which resulted in a dark purple solution that was
cooled to 0 8C. Arene 2 (4.1–10 equivs, see Table S5, Sup-
porting Information) was added followed by dropwise addi-
tion of TfOH (41 mL, 0.46 mmol), resulting in a colour
change to a yellow transparent solution. The solution was
stirred at the indicated temperature and time (Table S5,
Supporting Information). Work-up and purification was per-
formed as described above.
Experimental Section
General Experimental Conditions
The reactions were carried out in sealed tubes to allow for
reaction temperatures above the boiling point of CH2Cl2,
and were run without precaution to avoid moisture or air,
i.e., without inert gas or dried solvent. TfOH (ꢀ99%) was
stored under an argon atmosphere. New, commercially avail-
able cans of mCPBA were found to contain large and varia-
ble amounts of H2O. The mCPBA needs to be dried under
vacuum at room temperature for 1 h to obtain reproducible
results. The percentage of active oxidizing agent in mCPBA
was determined by iodometric titration.[36] All other chemi-
cals were used as received without further purification. Re-
action times and temperatures for each salt together with
analytical data for all novel salts are given in the Supporting
Information.
Acknowledgements
This work was financially supported by the Swedish Research
Council,Wenner-Gren Foundations and the Department of
Organic Chemistry at Stockholm University.
References
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General Procedure for the Synthesis of Salts 3 from
Iodoarenes and Arenes
The reactions were generally performed with 2 equivalents
of triflic acid, unless this resulted in by-product formation or
long reaction times. m-Chloroperbenzoic acid (65% active
oxidant, 66 mg, 0.26 mmol) and aryl iodide 1 (0.23 mmol)
were dissolved in CH2Cl2 (1 mL) in a sealed tube. The arene
2 (0.26 mmol) was added and the solution was cooled to 0
8C or the tabulated temperature (if lower, see Table S4,
Supporting Information) followed by dropwise addition of
TfOH (40–60 mL, 0.46–0.69 mmol), resulting in a coloured
solution. The reaction mixture was stirred at the indicated
temperature and time (see Table S4, Supporting Informa-
tion) and subsequently concentrated under vacuum (while
still cold for low-temperature reactions). Et2O (1 mL) was
added and the mixture was stirred at room temperature for
10 min to precipitate out an off-white solid. To ensure com-
plete precipitation, the flask was stored in the freezer for at
least 30 min before the solid was filtered off, washed with
Et2O and dried under vacuum to give diaryliodonium salt 3.
Procedure for Electron-Rich Arenes 2mand 2n
Performed as described above apart from the fact that the
arene was added at low temperature after an initial oxida-
tion period at higher temperature with the remaining re-
agents present, see Table S4 (Supporting Information) for
details.
Adv. Synth. Catal. 2007, 349, 2610 – 2618
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
2617