Highly efficient Barbier allylation from allyl alcohol using iridium(I)/tin(II): Unusual and indirect roles of allyl alcohol and tin

A reagent combination of SnCl2 and catalytic [Ir(COD)Cl]2 (1 mol%) in THF–H2O promotes the reaction of allyl alcohol and aldehyde leading to homoallyl alcohols in good to excellent yields. Control studies suggest the plausible participation of π-allyl-iridium intermediate(s) from which direct allyl transfer takes place to aldehyde.

Facile one-carbon homologation of allyl alcohol to homoallyl alcohol using IrI–SnCl2 as reagent is described, which might involve the intermediacy of a π-allyl-iridium intermediate. Figure optionsDownload as PowerPoint slide