Halogen-Bonding-Induced Conjugate Addition of Thiophenes to Enones and Enals.

Herein, we report the conjugate addition of α,β-unsaturated carbonyl compounds to thiophene derivatives. We used a 2-iodoimidazolinium triflate salt as a halogen-bonding donor, which afforded moderate-to-excellent yields of the corresponding alkylated thiophenes. Insight into the catalytic process was obtained from 1 H NMR spectroscopy studies and DFT calculations, which indicated a halogen-bonding-supported mechanism with limited Brønsted acid catalysis.