Formation of thiophene carboxylic acids from ?-diketones and dialkyl thiodiacetates:
Hinsberg Synthesis of Thiophene Derivatives
H. Wynberg, D. J. Zwanenburg, J. Org. Chem. 29, 1919 (1964); H. Wynberg, H. J. Kooreman, J. Am. Chem. Soc. 87, 1739 (1965); A. Birch, D. A. Crombie, Chem. Ind. 1971, 177; D. J. Chadwick et al., J. Chem. Soc. Perkin Trans. I 1972, 2079
