Synlett 2004(15): 2794-2796  
DOI: 10.1055/s-2004-836025
LETTER
© Georg Thieme Verlag Stuttgart · New York

Bismuth Triflate-Catalyzed Fries Rearrangement of Aryl Acetates

Thierry Ollevier*, Valerie Desyroy, Muhammad Asim, Marie-Christine Brochu
Département de Chimie, Université Laval, Québec (Québec), G1K 7P4, Canada
Fax: +1(418)6567916; e-Mail: thierry.ollevier@chm.ulaval.ca;
Further Information

Publication History

Received 27 July 2004
Publication Date:
25 November 2004 (online)

Abstract

Bismuth triflate was found to be an efficient catalyst in the Fries rearrangement of phenyl or 1-naphthyl acetates. Both reactions proceeded smoothly with a catalytic amount of bismuth triflate (10 mol%) to afford the corresponding hydroxyaryl ketone in moderate to good yields in most cases.

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Interestingly, a metal triflate screening for the catalytic Fries rearrangement was independantly studied by C. Le Roux. [2d] He showed that Bi(OTf)3 was slightly less efficient than Sc(OTf)3 but could get a synergistic effect using Bi(OTf)3 + MeSO3H.

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Nitroethane is a good alternative to potentially explosive nitromethane in the presence of a Lewis acid.

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A representative procedure for the Bi(OTf)3-catalyzed Fries rearrangement is at follows: To a solution of acetate 1 or 4 (1.00 mmol) in the solvent (2 mL) was added Bi(OTf)3·4H2O (0.10 mmol). The mixture was magnetically stirred and heated at 110 °C for 3-33 h. The reaction mixture was quenched by the addition of H2O, extracted with Et2O, dried over anhyd Na2SO4, filtered, and concentrated under vacuum (rotary evaporator). The residue was purified by column chromatography on silica gel using hexanes-EtOAc (99:1-90:10) as eluent. All the compounds were characterized by IR and 1H NMR spectroscopy, and accord exactly with those that have been previously reported in the literature.