The generation of ε-carbonyl cations and their reactions with nucleophiles is accomplished readily without transition metal cation stabilization, using the ε-bromide dienoate or dienone starting materials and GaCl3 or InCl3 catalysis. Arene nucleophiles are somewhat more straightforward than allyltrimethylsilane, but allyltrimethylsilane and propiophenone trimethysilyl enol ether each react successfully with InCl3 catalysis. The viability of these cations is supported by DFT calculations.
Keywords: allylation; catalysis; electrophilic aromatic substitution; umpolung; ε-carbonyl cations.
