Direct Synthesis of α-Iodoenones by IPy2BF4-Promoted Rearrangement of Propargylic Esters

A direct access to alpha-iodoeones from iodonium ion and propargylic tosylates or acetates is described. Bis(pyridine) iodonium tetrafluoroborate (IPy2BF4, Barluenga's reagent) promotes the rearrangement of these propargylic alcohol derivatives in mild conditions. The transformation gives beta-unsubstituted, beta-monosubstituted, and beta,beta-disubstituted alpha-iodoenones in high yields. beta-Substituted alpha-iodoenones are obtained with excellent (Z)-selectivity.