Aldol condensation benzofuran

Intramolecular aldol/Perkin type condensation of orf/to-formylaryloxyacetic acids and arylthioacetic esters produces benzofuran- and benzothiophene-2-esters respectively, as illustrated below. The synthesis can be performed in one pot, thus ortfto-hydroxyaryl-aldehydes or -ketones, are 0-alkylated with a-halo-ketones, then intramolecular aldol condensation in situ produces 2-acyl or 2-aroyl-benzofurans. ° For benzothiophenes, the ring-closure substrates can also be obtained via methyl thioacetate displacement of fluoride from orf/to-fluoro-araldehydes. ... 

Intramolecular aldol/Perkin type condensation of aryloxyacetic acids and arylthioacetic esters produces benzofuran and benzothiophene-2-esters respectively. The examples shown illustrate contrasting methods - classical and modem - for the preparation of the required starting materials. 

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