Synlett 2008(10): 1455-1458  
DOI: 10.1055/s-2008-1078420
LETTER
© Georg Thieme Verlag Stuttgart · New York

Copper-Catalyzed Sulfonylation of Arylboronic Acids in Ionic Liquids

M. Lakshmi Kantam*, B. Neelima, B. Sreedhar, Rajashree Chakravarti
Inorganic & Physical Chemistry Division, Indian Institute of Chemical Technology, Hyderabad 500607, India
Fax: +91(40)27160921; e-Mail: mlakshmi@iict.res.in;
Further Information

Publication History

Received 19 March 2008
Publication Date:
16 May 2008 (online)

Abstract

Cupric acetate in ionic liquids (ILs) catalyzes coupling reaction of arylboronic acids with sulfinic acid salts to afford aryl sulfones in good yields under ambient conditions. This mild and efficient cross-coupling reaction gives access to a wide range of al­kylaryl and diaryl sulfones in good yields. The use of ionic liquid allows for easy separation of the product and recycling of copper catalyst.

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Ionic liquids were synthesized according to the procedures reported in the literature and their purity was confirmed by 1H NMR and TGA-DTA analysis.19
General Procedure for the Preparation of Sulfones: To a solution of Cu(OAc)2 (0.013 g, 10 mol%) in ionic liquid (1 mL) and arylboronic acid (1 mmol), sodium sulfinate salt (1 mmol) was added and stirred at r.t. for 12 h. After completion of the reaction, as monitored by TLC, the crude product was extracted with Et2O (3 × 10 mL). The combined Et2O extracts were concentrated in vacuo and the resulting product was purified by column chromatography on silica gel with EtOAc-n-hexane (2:8) as eluent to afford the desired product. The products were characterized by comparison of their NMR and mass spectra with those reported in the literature.12c,14 The ionic liquid containing Cu(OAc)2 was dried under vacuum and preserved for the next run.