Pd(0)/iodide salt-mediated Heck reaction of aryl nonaflates: Application to the synthesis of 2-(1-alkenyl)phenylphosphonates

Iodide salt, such as NaI, KI or n-Bu4NI (TBAI), rather than bromide or chloride salt, was found to play a key role in the Pd(0)-catalyzed Heck reaction of aryl nonaflates and terminal alkenes. In the presence of PdCl2(PPh3)2, NaI or TBAI in DMF, a class of 2-(1-alkenyl)phenylphosphonates was first synthesized via the reaction of o-phosphonylphenyl nonaflates with alkenes, the yields, regioselectivities and stereoselectivities were much dependent on the nature of the substituents. In case of the aryl nonaflates without bearing the sterically hindered phosphonyl group with the alkenes, the reactions proceeded more smoothly under the same conditions, leading to the linear products regioselectively in good to excellent yields. A rationale for this reaction is discussed.