ipso-Nitration of Arylboronic Acids with Chlorotrimethylsilane-Nitrate Salts G. K. Surya Prakash,* Chiradeep Panja, Thomas Mathew, Vijayalakshmi Surampudi, Nicos A. Petasis, and George A. Olah* Loker Hydrocarbon Research Institute and Department of Chemistry, UniVersity of Southern California, Los Angeles, California 90089-1661 gprakash@usc.edu Received April 13, 2004 ABSTRACT A mixture of nitrate salt and chlorotrimethylsilane is found to be an efficient regioselective nitrating agent for the ipso-nitration of arylboronic acids to produce the corresponding nitroarenes in moderate to excellent yields. High selectivity, simplicity, and convenience are the key features of the reaction. Nitration of aromatic compounds is one of the most extensively studied reactions, 1 and nitroaryl moieties play key roles in the physical and chemical properties of many target molecules in organic synthesis. For electrophilic nitration of aromatic compounds, a wide variety of reagents 2,3 are available to date. Most of them are very strong nitrating agents and often lead to further nitration and mixture of isomers. Since most nitrating agents are oxidants, oxidation of other functional groups can also occur, giving a mixture of products. Thus, a search for milder and selective nitrating agents is a good research goal. In the last few decades, arylboronic acids 4 have been extensively used as versatile synthons in organic synthetic transformations involving various reactions such as Suzuki coupling 5 and multicom- ponent reactions for the synthesis of various amino acids and trifluoromethylated amines. 6,7 Fluorination of various derivatives of aryl/alkenylboronic acids has been reported. 8 In earlier studies, we have shown regeoselective halogena- tion 9 and nitration 10 of arylboronic acids with N-halosuccin- imides and Crivello’s reagent 11 (ammonium nitrate/trifluro- acetic anhydride), respectively. However, during nitration with the relatively powerful Crivello’s reagent, dinitration was also observed and the temperature had to be carefully regulated to avoid undesirable side reactions. Herein we report a simple, convenient and mild method for the ipso-nitration of arylboronic acids using inorganic nitrate salt and chlorotrimethylsilane. This method provides the ipso-nitrated product in moderate to high yield (∼95- 98% purity for the crude product itself) and is found to be more selective than our previously reported method using Crivello’s reagent. 11 The reaction is easy to perform, and workup avoids further purification in many cases. Another (1) (a) Olah, G. A.; Malhotra, R.; Narang, S. C. Nitration: Methods and Mechanisms; VCH: New York, 1989. (b) Kuhn, S. J.; Olah, G. A. J. Am. Chem. Soc. 1961, 83, 4564. (c) Schofield, K. Aromatic Nitration; University Press: Cambridge, 1980. (2) Olah, G. A.; Kuhn, S. J. J. Am. Chem. Soc. 1962, 84, 3684. (3) Olah, G. A.; Prakash, G. K. S.; Wang, Q.; Li, X. In Encyclopedia of Reagents for Organic Synthesis; Paquette, L. A.; Wiley: Chichester, 1995; Vol. 6. (4) Negishi, E. Comp. Organomet. Chem. 1983, 7, 323. (5) Miyaura, N.; Yanagi, T.; Suzuki, A. Synth. Commun. 1981, 11, 513. (6) (a) Hassan, J.; Sevignon, M.; Gozzi, C.; Schulz, E.; Lemaire, M. Chem. ReV. 2002, 102 (5), 1359 and references therein. (b) Petasis, N. A.; Boral, S. Tetrahedron Lett. 2001, 42 (4), 539. (c) Petasis, N. A.; Goodman, A.; Zavialov, L. A. Tetrahedron 1997, 53 (48), 16463. (7) Prakash, G. K. S.; Mandal, M.; Schweizer, S.; Petasis, N. A.; Olah, G. A.J. Org. Chem. 2002, 67 (11), 3718 and references therein. (8) (a) Diorazio, L. J.; Widdowson, D. A.; Clough, J. M. Tetrahedron 1992, 8 (37), 8073. (b) Petasis, N. A.; Yudin, A. K.; Zavialov, L. A.; Prakash, G. K. S.; Olah, G. A. Synlett 1997, 5, 606. (9) Thiebes, C.; Prakash, G. K. S.; Petasis, N. A.; Olah, G. A. Synlett 1998, 141. (10) Stefan, S.; Jurgen, S.; Prakash, G. K. S.; Petasis, N. A.; Olah, G. A. Synlett 2000, 1485. (11) Crivello, J. V. J. Org. Chem. 1981, 46, 3056. ORGANIC LETTERS 2004 Vol. 6, No. 13 2205-2207 10.1021/ol0493249 CCC: $27.50 © 2004 American Chemical Society Published on Web 06/02/2004