Carbonylative Sonogashira coupling of terminal alkynes with aqueous ammonia

graphic Carbonylative coupling of phenylethyne with 4-methoxy-1-iodobenzene in the presence of 1 mol % PdCl2(PPh3)2, 2 equiv of 0.5 M aqueous ammonia, and CO (1 atm) gives the corresponding alpha,beta-alkynyl ketone in 72% isolated yield after stirring at room temperature for 41 h, while noncarbonylative coupling product is not obtained.