6-Trimethylstannylcoumarins 2, conveniently obtained from the correspo
nding 4-triflyloxycoumarins 1, undergo Pd(0)/CuI-cocatalyzed cross-cou
pling reactions with a variety of aryl iodides to afford 4-arylcoumari
ns 4 in moderate to good yields. Aryl triflates are less effective as
coupling partners.