cross‐dehydrogenative coupling of arene carboxylicacids with olefins is reported with ruthenium(II) catalyst employing air and water as green oxidant and solvent, respectively. It offers a robust synthesis of valuable phthalide molecules. A one‐pot sequential strategy is also disclosed to access Heck‐type products that are apparently difficult to make directly from arene carboxylicacids.
The ortho-olefination of benzoic acids can be achieved effectively through rhodium-catalyzed oxidative coupling with alkenes. The carboxylic group is readily removable to allow ortho-olefination/decarboxylation in one pot. alpha,beta-Unsaturated carboxylic acids such as methacrylic acid also undergo the olefination at the beta-position. Under the rhodium catalysis, the cine-olefination of heteroarene carboxylic acids such as thiophene-2-carboxylic acid proceeds smoothly accompanied by decarboxylation to selectively produce the corresponding vinylheteroarene derivatives.