Generation and Reactions of ε-Carbonyl Cations via Group 13 Catalysis

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.