Generation of gamma-functionalized alkynyl ligands by migratory insertion of an allenylidene unit into a M-OR bond

The hydroxyrhodium(I) complexes 2a,b, which are prepared from the corresponding chloro derivatives 1a,b and KOBu(t), react with acetic acid and phenol at room temperature to give the new acetato and phenolate metal compounds 3a,b and 4a,b almost quantitatively; subsequent treatment of 3a,b and 4a,b with CO leads to migratory insertion of the allenylidene unit into the Rh-OR bond to yield gamma-functionalized alkynyl ligands.