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Transition-Metal-Free Synthesis of Oxindoles by Potassium tert-Butoxide-Promoted Intramolecular α-Arylation

Astrid Beyer, Julien Buendia and Carsten Bolm*

*Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, D-52074 Aachen, Germany, Email: carsten.bolmoc.rwth-aachen.de

A. Beyer, J. Buendia, C. Bolm, Org. Lett., 2012, 14, 3948-3951.

DOI: 10.1021/ol301704z


Abstract

Potassium tert-butoxide-mediated intramolecular α-arylations of fluoro- and chloro-substituted anilides provide oxindoles in DMF at 80C. Diversely substituted products have been obtained in good yields.

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Oxindole syntheses:

The anilide (150 mg, 1.0 equiv) and KOt-Bu (1.2 - 3.0 equiv) were placed in a sealable tube equipped with a magnetic stir bar. The tube was covered with a rubber septum, an argon atmosphere was established and dry DMF (2 mL) was added by syringe. The septum was replaced by a teflon-coated screw cap and the reaction mixture was stirred for 16-24 hours at 80 C. Then, the resulting mixture was cooled to ambient temperature and H2O (2 mL) and ethyl acetate (8 mL) were added. The two phases were separated and the aqueous layer was extracted with ethyl acetate (3 x 4 mL). The combined organic phases were washed with brine (1 x 10 mL), dried with Na2SO4, filtrated and concentrated under reduced pressure. The product was purified by column chromatography (n-pentane/ethyl acetate).


Key Words

Oxindoles


ID: J54-Y2012-2450