Regioselective hydrocarbonylation of phenylacetylene to α,β-unsaturated esters and thioesters with Fe(CO)5 and Mo(CO)6

A highly regioselective hydrocarbonylation of phenylacetylene with thiols and alcohols was developed using metal carbonyls/diazabicyclo[2.2.2]octane (DABCO) system at 100 °C in DMF. The use of Mo(CO)6 and thiols in the presence of DABCO was applied as an efficient Pd-free method for hydrothiocarbonylation of phenylacetylene into trans-α,β-cinamyl thioesters in excellent yields (88–98%). Similar reaction using Fe(CO)5/ROH/DABCO system resulted into high yield synthesis of trans-α,β-cinamyl esters (87–98%). These reactions were conducted under mild reaction conditions without the need to use gaseous CO or any phosphine ligand and palladium catalyst.