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A Catalyst-free, Efficient and Selective Synthesis of Asymetric Diarylsulfones
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1  INQUISUR, Departamento de Química, Universidad Nacional del Sur, Avda. Alem 1253, (8000) Bahía Blanca, Argentina

Abstract: Over the years, sulfones have emerged as interesting synthetic goals because they are valuable intermediates in organic synthesis1 as well as important building blocks in biologically active compounds.2 The usual procedures for their preparation are the oxidation of the corresponding sulfides and the sulfonylation of suitable arenes.3 Nevertheless, their scope of application is limited by the availability of sulfides and by the substituent-directing effects and the reactivity substrate requirements, respectively. On the other hand, the metal-mediated cross-coupling reactions between sulfinic acid salts and aryl derivatives (halides and triflates) are milder alternatives, although they imply the use of air or moisture sensitive reagents.4 In recent years, we have focused on arylstannanes as valuable and easily accessible reagents in C-C bond forming reactions through catalyst-free processes.5 Driven by these results and considering the importance of sulfones we initiated studies on the reaction of arylstannanes with sulfonyl chlorides. Now, we report the synthetic potential of this pair of reagents, under catalyst-free conditions, for the generation of asymmetric diarylsulfones, and its efficiency using diarylstannanes as starting substrates. Moreover, a special work up is carried out in order to recover the di- and trialkyltin chlorides generated. All the reactions studied went, exclusively, through an ipso-substitution and give acceptable yields of sulfones from aryl sulfonyl chlorides supporting either electron-releasing or electron-attracting substituents. 1 P.R. Blakemore, J. Chem. Soc. Perkin Trans. 1 2002, 2563. 2 a) R.C. Bernotas et al. Bioorganic & Medicinal Chemistry Letters 2010, 20, 209. b) S.A. Kolodziej et al. Bioorganic & Medicinal Chemistry Letters 2010, 20, 3561. 3 (a) M. Rahimizadeh et al. J. Mol. Catal. A: Chem. 2010, 323, 59. (b) A. Rostami et al. Tetrahedron Lett. 2010, 51, 3501. (c) S. Nara et al. J. Org. Chem. 2001, 66, 8616. 4 (a) D.C.Reeves et al. Tetrahedron Lett. 2009, 50, 3501. (b) K. Anirban et al. Org. Lett. 2007, 9, 3405. 5 (a) M.J.Lo Fiego et al. J. Org. Chem.2011, 76, 1707. (b) M.J. Lo Fiego et al. J.Organometal.Chem. 2009, 694, 3674. (c) M.J. Lo Fiego J. Org. Chem. 2008, 73, 9184. (d) G.F. Silbestri et al. J. Organometal. Chem. 2006, 691, 1520.
Keywords: Diarylsulfones, arylstannanes, sulfonylation, catalyst-free