/ Iodane-mediated and electrochemical oxidative transformations of 2-methoxy- and 2-methylphenols
6-Hydroxy-3,5,6-trimethylcyclohexa-2,4-dienone (3h) and 3,4,6-trimethyl-1,2-benzoquinone (9). SIBX-mediated oxidation of 2,3,5-trimethylphenol (1h, 500 mg, 3.6 mmol) was carried out according to the general procedure to afford, after a workup using saturated aqueous NaHCO3, a clean 1:1 mixture of the orthoquinol 3h and the 3,4,6-trimethyl-1,2-benzoquinone (9, 461 mg, ca. 83%). This dark reddish solid was separated by column chromatography, eluting with toluene/EtOAc (6:1), to give racemic 3h as an orange oil (68 mg, 12%). Compound 3h: IR (NaCl) 3456, 1667, 1642, 1572, 1161; 1H NMR (CDCl3, 300 MHz) d 1.34 (s, 3H), 1.99 (s, 3H), 2.00 (d, J = 1.5 Hz, 3H), 3.50 (s, 1H), 5.76 (bt, J = 1.5 Hz, 1H), 5.84 (s, 1H); 13C NMR (CDCl3, 75.5 MHz) d 206.4, 155.7, 154.9, 121.3, 118.6, 77.5, 29.2, 23.0, 17.6; EIMS m/z (rel intensity) 152 (M+, 26), 137 (12), 122 (100), 107 (27), 79 (95). Compound 9: 1H NMR (CDCl3, 300 MHz) d 1.88 (s, 3H), 1.91 (m, 3H), 2.04 (s, 3H), 6.62 (m, 1H); 13C NMR (CDCl3, 75.5 MHz) d 180.7, 179.9, 145.9, 141.5, 135.9, 132.9, 20.3, 15.0, 11.3. These NMR data were read on spectra of the crude product mixture; the ortho-quinone 9, as well as 7 and 8, did not resist silica gel chromatography. Acknowledgements We wish to thank SIMAFEX (www.simafex.com) and Dr. Dominique Depernet (dominique.depernet@simafex.com) for their scientific contribution and financial support, the Association Nationale de la Recherche Technique (CIFRE n° 301/2002), the Ministère de la Recherche, the Centre National de la Recherche Scientifique and the Conseil Régional d’Aquitaine (Bourse Docteur Ingénieur N°8006677) for A.O.’s, I.F.’s and M.O.’s graduate research assistantships. We also thank Frédéric Tep for his contribution to this work. References 1. Zhdankin, V. V.; Stang, P. J. Chem. Rev. 2002, 102, 2523. 2. Varvoglis, A. Hypervalent Iodine in Organic Synthesis; Academic Press: San Diego, 1997. 3. Varvoglis, A. Tetrahedron 1997, 53, 1179. 4. Stang, P. J.; Zhdankin, V. V. Chem. Rev. 1996, 96, 1123. 5. Varvoglis, A. Synthesis 1984, 709. 6. Koser, G. F. In The Chemistry of Functional Groups; Patai, S., Rappoport, Z., Eds.; Wiley: New York, 1983, pp 721-811. 7. Banks, D. F. Chem. Rev. 1966, 66, 243. 8. Koser, G. F. Aldrichimica Acta 2001, 34, 89. 9. Dess, D. B.; Martin, J. C. J. Org. Chem. 1983, 48, 4155. 10. Dess, D. B.; Martin, J. C. J. Am. Chem. Soc. 1991, 113, 7277. 11. Frigerio, M.; Santagostino, M. Tetrahedron Lett. 1994, 35, 8019.
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