The regioselective C3-alkenylation of thiophene-2-carboxylic acids can be achieved effectively via rhodium/silver-catalyzed oxidative coupling with alkenes, unaccompanied by decarboxylation. A wide range of substrates including brominated thiophenecarboxylic acids and furan-2-carboxylic acids can be employed together with styrenes as well as acrylates. The present catalyst system is also applicable to ortho-alkenylation of benzoic acids.

The reaction of N‐[2.2]paracyclophanyl‐substituted amides or amines with phenyliodine diacetate (PIDA) and protic nucleophiles affords mixed para‐substituted [2.2]paracyclophane derivatives in moderate to good yields. As protic nucleophiles carboxylic acids and alcohols as well as pyridine hydrobromide can be used. 4‐Hydroxy[2.2]paracyclophane reacts in an analogous manner.magnified image

Rhodium-Catalyzed C3-Selective Alkenylation of Substituted Thiophene-2--carboxylic Acids and Related Compounds. -This regioselective alkenylation affords a wide range of different alkenylated thiophene derivatives and gives also access to the corresponding alkenylated furans, benzofurans, and benzoic acids. -(IITSUKA, T.; SCHAAL, P.; HIRANO, K.; SATOH, T.; BOLM, C.; MIURA*, M.; J. Org. Chem. 78 (2013) 14, 7216-7222, http://dx.