Substitution of allylic alcohols to form a carboncarbonbond is accomplished by a simple reaction of the allylic alcohol itself with an enoxysilane, catalyzed by [Ir(cod)(PPh3)2]X which is activated by H2 molecule. The anion part X of the complexes plays an important role to enhance the rate and product yields of the reactions. The efficacy of the catalyst increases with switching X in the order of