Thiophene-2-carboxylic acid explained

Thiophene-2-carboxylic acid is an organic compound with the formula SC₄H₃CO₂H. It is one of two monocarboxylic acids of thiophene, the other being thiophene-3-carboxylic acid.^[1] Copper(I) thiophene-2-carboxylate is a catalyst for Ullmann coupling reactions.

Synthesis

It can be prepared by the oxidation of thiophene-2-carboxaldehyde or, more practically, 2-acetylthiophene.^[2]

Applications and reactions

thumb|left|Suprofen, which is produced from thiophene-2-carboxylic acid, is the active ingredient in some eye drops.Upon treatment with LDA, thiophene-2-carboxylic acid undergoes double deprotonation to give the 5-lithio derivative, a precursor to many 5-substituted derivatives.^[3]

Thiophene-2-carboxylic acid has been widely studied as a substrate in coupling reactions and olefinations.^{[4] [5]}

References

1. 10.15227/orgsyn.033.0094. E. Campaigne, William M. LeSuer. 3-Thenoic Acid. Organic Syntheses. 1953. 33. 94.
2. Book: Swanston, Jonathan . Thiophene . Ullmann's Encyclopedia of Industrial Chemistry . Wiley-VCH . Weinheim . 2006 . 10.1002/14356007.a26_793.pub2. 3527306730 . .
3. Generation and Synthetic Utility of Dianions Derived from Thiophenecarboxylic Acids. Knight, David W.; Nott, Andrew P.. Journal of the Chemical Society, Perkin Transactions 1. 1983. 791–4. 10.1039/p19830000791.
4. 10.1126/science.1128684. Synthesis of Biaryls via Catalytic Decarboxylative Coupling. 2006. Gooßen. Lukas J.. Deng. Guojun. Levy. Laura M.. Science. 313. 5787. 662–664. 16888137. 2006Sci...313..662G. 1781760.
5. 10.1021/ja109676d. Rh(III)-Catalyzed Directed C−H Olefination Using an Oxidizing Directing Group: Mild, Efficient, and Versatile. 2011. Rakshit. Souvik. Grohmann. Christoph. Besset. Tatiana. Glorius. Frank. Journal of the American Chemical Society. 133. 8. 2350–2353. 21275421.