Synlett 2002(5): 0735-0738
DOI: 10.1055/s-2002-25345
LETTER
© Georg Thieme Verlag Stuttgart · New York

Selective Sulfonylation of Arenes and Benzoylation of Alcohols Using Lithium Perchlorate as a Catalyst Under Neutral Conditions

B. P. Bandgar*, V. T. Kamble, V. S. Sadavarte, L. S. Uppalla
Organic Chemistry Research Laboratory, School of Chemical Sciences, Swami Ramanand Teerth Marathwada University, Handed-431 606, India
Fax: +91(2462)29245; e-Mail: vtkd@redifffmail.com;
Further Information

Publication History

Received 16 October 2001
Publication Date:
07 February 2007 (online)

Abstract

Sulfonylation of aromatics with p-toluenesulfonyl chloride and benzoylation of alcohols with benzoyl chloride using lithium perchlorate as a catalyst is described. The remarkable selectivity under neutral conditions is an attractive feature of this method

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A Typical Procedure for Sulfonylation of Arenes: A mixture of anisole (10 mL), p-toluene sulfonyl chloride (2 mmol) and lithium perchlorate (0.4 mmol) was refluxed for 2.5 h. On completion of the reaction, the mixture was cooled and excess anisole was removed under reduced pressure. To the residue chloroform (10 mL) and water (10 mL) was added. The aq layer was washed with chloroform (3 × 5mL). The combined organic layer was dried with anhyd Na2SO4 and removal of the solvent under vacuum furnished crude product, which was further purified by column chromatography.
Yield = 90%; mp = 149 °C; IR (KBr): 683, 834, 1007, 1360, 1599, 2910, 3300 cm-1; 1H NMR (300 MHz, CDCl3): δ = 2.36 (s, 3 H, CH3), 3.81 (s, 3 H, OCH3), 6.95 (d, 2 H, J = 8.3 Hz, Ar-H), 7.31 (d, 2 H, J = 7.4 Hz, Ar-H), 7.85 (d, 2 H, J = 8.3 Hz, Ar-H), 7.90 (d, 2 H, J = 7.4 Hz, Ar-H).

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Typical Procedure for Benzoylation: A mixture of benzyl alcohol (5 mmol), benzoyl chloride (5 mmol) and LiClO4 (1 mmol) was stirred for 7 h at 25 °C (Table [3] , entry 3). After completion of the reaction (TLC), the solvent was removed under reduced pressure and the product was purified by column chromatography on silica gel. Yield = 80%; IR(neat): 712, 1065, 1107, 1272, 1450, 1716 cm-1; 1H NMR (CDCl3): δ = 4.4 (s, 2 H), 7.3-7.4 (m, 5 H), 8.1-8.15 (m, 5 H); 13C NMR: δ = 70.2, 125.8, 127.77, 128.42, 128.61, 129.74, 130.55, 133.02, 141.78, 145.81, 175.9.