Iridium complex-catalyzed carbonylation of allylic phosphates

[Ir(cod)Cl]2 with a ligand such as P(2-furyl)3, PPh2C6F5 or AsPh3 showed high catalytic activity for the carbonylation of allylic phosphates in the presence of alcohols to give the corresponding β,γ-unsaturated esters. The carbonylation of diethyl (E)-3-phenyl-2-propenyl phosphate in the presence of EtOH under an initial carbon monoxide pressure of 40 kg cm−2 at 100 °C gave ethyl (E)-4-phenyl-3-butenoate in 90% yield. No (Z)-isomer was obtained. The reaction proceeded smoothly without using an amine as an additive. The carbonylation of 2-alkenyl diethyl phosphates in the presence of EtOH gave a mixture of ethyl (E)- and (Z)-3-alkenoate. The stereochemistry of the starting material was lost by syn–anti isomerization of the π-allyl iridium intermediate prior to the insertion of carbon monoxide into the iridiumcarbon bond. Increasing the steric bulkiness of the substituent at the γ-position of the allyl system or increasing the initial carbon monoxide pressure increased the selectivity for a product with the same stereochemistry as the starting material.