Reactivity of a 10-I-3 hypervalent iodine trifluoromethylation reagent with phenols.
The reaction of the 10-I-3 hypervalent iodine electrophilic trifluoromethylation reagent 1-trifluoromethyl-1,2-benziodoxol-3-(1H)-one (2) with 2,4,6-trimethylphenol, after deprotonation with NaH and in the presence of 18-crown-6 in a polar, nonprotic solvent, affords 1,3,5-trimethyl-2-(trifluoromethoxy)benzene (4) only as a byproduct. Trifluoromethylation occurs preferentially at the ortho- and para-positions of the aromatic core, giving the corresponding trifluoromethylcyclohexadienones 5 and 6. In case the ortho- and/or para-positions are not substituted, the corresponding products of an aromatic, electrophilic substitution are obtained in moderate yield, for example, 2-trifluoromethyl-4-tert-butylphenol (10a) from 4-tert-butylphenol (10).
Stanek
Kyrill
K
Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology, ETH Zurich, CH-8093 Zürich, Switzerland.
Koller
Raffael
R
Togni
Antonio
A
D054879:Halogenation; D006845:Hydrocarbons, Fluorinated / Q000737:chemistry*; D007455:Iodine / Q000737:chemistry*; D010636:Phenols / Q000737:chemistry*
D006845:Hydrocarbons, Fluorinated; D010636:Phenols; D007455:Iodine