Iridium-Catalyzed Allylic Etherification and Its Application

摘要

pi-Allyliridium(III) complexes can be prepared from iridium(I) complexes such as [IrCl(cod)]_2 and allylic esters at room temperature to undergo nucleophilic substitutions. We have found that tin(II) chloride mediates the formation of pi-allyliridium complexes from allylic alcohols to cause carbonyl allylation. ~1H NMR observation of the reaction of 2-propen-1-ol with tin(II) chloride in the presence of a catalytic amount of [IrCl(cod)]_2 in THF-d_8 at room temperature with neither aldehyde nor H_2O detected di-2-propenyl ether. Thus, we supposed the equilibrium between allylic ether and allylic alcohol in the presence of iridium catalyst, alcohol and tin(II) chloride, and then hoped for either allylation of alcohols or deallylation of allyl alkyl ethers with iridium catalyst and tin(II) chloride. We here report iridium-catalyzed allylic etherifications of various alcohols via the formation of pi-allyliridium complexes from allylic alcohols with tin(II) chloride.