Synlett 2007(14): 2209-2212  
DOI: 10.1055/s-2007-985559
LETTER
© Georg Thieme Verlag Stuttgart · New York

o-Benzenedisulfonimide: A Novel and Reusable Catalyst for Acid-Catalyzed Organic Reactions

Margherita Barbero*, Silvano Cadamuro, Stefano Dughera, Paolo Venturello
Dipartimento di Chimica Generale ed Organica Applicata dell’Università, Via Pietro Giuria, 7, 10125 Torino, Italy
Fax: +39(011)6707642; e-Mail: margherita.barbero@unito.it;
Further Information

Publication History

Received 8 June 2007
Publication Date:
24 July 2007 (online)

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Abstract

The o-benzenedisulfonimide is used as Brønsted acid in catalytic amounts in various acid-catalyzed organic reactions, such as etherification, esterification, and acetalization; the conditions required are mild and in the considered examples the results are always good. A useful aspect of the use of this catalyst is its easy recovery in high yield from the reaction mixture and its reuse in ­other reactions, with economic and ecological advantages.

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Typical Procedure for o -Benzenedisulfonimide-Catalyzed Etherification (Entry 1, Table 1) To a solution of 1,3-diphenylprop-2-en-1-ol (3; 0.42 g, 2.0 mmol) in abs. EtOH (10 mL) was added o-benzenedisulfon-imide (1; 5 mol%; 0.02 g, 0.1 mmol); the reaction mixture was stirred at r.t. The reaction was monitored by TLC (PE-Et2O, 6:4), GC, and GC-MS analyses until complete disappearance of the starting material. Then the reaction mixture was evaporated under reduced pressure and the residue was poured into Et2O-H2O (40 mL, 1:1). The aqueous layer was separated. The organic extract was washed with H2O (20 mL), dried over Na2SO4, and evaporated under reduced pressure. The crude residue was chromatographed on a short column (PE-Et2O, 6:4) to provide pure (E)-1,3-diphenyl-3-ethoxyprop-1-ene (4a; GC, GC-MS, TLC, 1H NMR) in 77% yield (0.37 g); colorless oil. 1H NMR: δ = 1.33 (t, J = 7.0 Hz, 3 H), 3.60 (superimposed q, J = 7.0 Hz, 2 H diastereotopic), 4.98 (d, J = 6.8 Hz, 1 H), 6.38 (dd, J = 16.0, 6.8 Hz, 1 H), 6.68 (d, J = 16.0 Hz, 1 H), 7.25-7.50 (m, 10 H). 13C NMR: δ = 15.72, 64.33, 82.86, 126.93 (2 C), 127.17 (2 C), 127.94, 128.00, 128.84 (4 C), 131.00, 131.45, 136.97, 141.86. MS (EI, 70 eV): m/z (%) 238 (70) [M+], 105 (100).

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Typical Procedure for o -Benzenedisulfonimide-Catalyzed Esterification (Entry 5, Table 1) To a solution of phenylacetic acid (5; 0.27 g, 2.0 mmol) and butan-1-ol (0.16 g, 2.2 mmol) in toluene (10 mL) was added o-benzenedisulfonimide (1; 25 mol%; 0.11 g, 0.5 mmol) and the reaction mixture was stirred at 90 °C for 30 min. After the usual workup, the crude residue was chromatographed on a short column (PE-Et2O, 8:2) to provide pure butyl phenylacetate (6a; GC, GC-MS, TLC, 1H NMR) in 90% yield (0.38 g); colorless oil with spectral data identical to those reported. [22d] 1H NMR: δ = 0.85 (t, J = 7.0 Hz, 3 H), 1.23-1.34 (m, 2 H), 1.48-1.58 (m, 2 H), 3.56 (s, 2 H), 4.04 (t, J = 6.6 Hz, 2 H), 7.15-7.28 (m, 5 H). 13C NMR: δ = 13.86, 19.27, 30.80, 41.66, 64.94, 127.21, 128.72 (2 C), 129.43 (2 C), 134.40, 171.88; MS (EI, 70 eV): m/z (%) = 192 (5) [M+], 91 (100).

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The aqueous layer and aqueous washing from the various reactions were collected and evaporated under reduced pressure. The residue was passed through a column of Dowex 50X8 ion-exchange resin (1.6 g for 1 g of product), eluting with H2O (about 35 mL). After removal of H2O under reduced pressure, virtually pure (1H NMR) o-benzenedisulfonimide(1) was recovered; mp 192-194 °C, from toluene (lit. 3: mp 192-194 °C).