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Synlett 1995; 1995(2): 177-179
DOI: 10.1055/s-1995-4913
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[2+2] Cycloaddition of Benzyne and Ketene Silyl Acetal as an Efficient Route to Benzocyclobutenones

Takamitsu Hosoya, Takayuki Hasegawa, Yokusu Kuriyama, Takashi Matsumoto, Keisuke Suzuki*
  • *Department of Chemistry, Keio University, Hiyoshi, Kohoku-ku, Yokohama 223, Japan
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Publication Date:
31 December 2000 (online)

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New and efficient synthetic approach to benzocyclobutene derivatives is described. Halogen-lithium exchange of ortho-halo aryl triflates (THF, -78°C) quickly generates arynes which react with the coexisting ketene silyl acetals to give [2+2] cycloadducts in high yields. The polarization of the aryne species induced by an adjacent alkoxyl group (inductively electron withdrawing) directs the regioselectivity of the cycloadditions. Subsequent acetal cleavage under acidic conditions gives various benzocyclobutenones in high yields.

Benzyne - Ketene silyl acetal - [2+2] Cycloaddition - Benzocyclobutenone - Regioselective

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