Stanek Kyrill, Koller Raffael, Togni Antonio
Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology, ETH Zurich, CH-8093 Zürich, Switzerland.
J Org Chem. 2008 Oct 3;73(19):7678-85. doi: 10.1021/jo8014825. Epub 2008 Sep 5.
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).
10-I-3高价碘亲电三氟甲基化试剂1-三氟甲基-1,2-苯并碘氧杂环戊-3-(1H)-酮（2）与2,4,6-三甲基苯酚反应，在用NaH去质子化后，于极性非质子溶剂中在18-冠-6存在下，仅得到副产物1,3,5-三甲基-2-(三氟甲氧基)苯（4）。三氟甲基化优先发生在芳环核心的邻位和对位，生成相应的三氟甲基环己二烯酮5和6。如果邻位和/或对位未被取代，则以中等产率得到芳族亲电取代的相应产物，例如，由4-叔丁基苯酚（10）得到2-三氟甲基-4-叔丁基苯酚（10a）。
