Copper-Catalyzed Hydrocarboxylation of N-Allenyl Derivatives.

The addition of carboxylic acids to allenes was performed with copper catalysis. This hydrocarboxylation reaction, occurring on the terminal carbon of the allenes, is totally regio- and stereoselective. It represents the first copper-catalyzed example of intermolecular C-O bond formation by allene hydrofunctionalization. This ligand-free system is based on the use of catalytic amounts of copper combined with a base (10 mol % of K2CO3).