ε-Amido-allylindiums generated from N-Ts-β-lactams in the presence of 2 eq. of InI, catalytic amounts of Pd(PPh3)4 and 5 eq. of CF3CO2H react regio- and stereoselectively with a number of aromatic and aliphatic aldehydes to afford γ-butyrolactones as the exclusive products in high yield.
