Efficient route for the synthesis of 3,4-cycloalkoxy-2,5-diethoxycarbonyl-thiophenes obtained with bulky alkyl dibromides using trialkylamines as base-solvent |
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Authors: | Bernardo A Frontana-Uribe Jürgen Heinze |
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Institution: | a Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior Ciudad Universitaria, 04510, DF, Mexico b Freiburg Materials Research Center, Albert-Ludwig University of Freiburg, Stefan-Meier Strasse 21, D-79104 Freiburg, Germany |
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Abstract: | New reaction conditions were investigated for dialkylizing diethyl 3,4-dihydroxy-2,5-thiophenedicarboxylate with sterically hindered alkyl-dibromides, using as reaction system DMF-trialkylamine or only the trialkylamine as base-solvent. This methodology produced the corresponding 3,4-cycloalkoxy-2,5-diethoxycarbonyl-thiophene derivatives faster and with better yields than those reported previously for K2CO3-DMF. Experiments were performed with triethylamine, tripropylamine, and tributylamine. Tributylamine produced the best results in a general reaction with alkyl-bromides. Aromatic amines like N,N-dimethylaniline, N-methyldiphenylamine, and triphenylamine failed to react at all. Reactions using only the tributylamine as base-solvent demonstrated that DMF is not necessary as a solvent to obtain good yields. |
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Keywords: | Nucleophilic substitution Heterocycles Thiophenes Alkoxy-thiophenes Conducting polymers Polythiophenes |
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