Effects of Linker Structures in Designing Perfluoroiodobenzene- Based Halogen-Bond Donor Catalysts with Two-Point Activation Modes

Linker structures were systematically investigated for use in designing halogen-bond donor catalysts with two-point activation modes based on perfluoroiodobenzenes. Tetrafluorophenylene, phenylene, and acetylene were examined as potential linkers, and perfluoroiodobenzenes containing these linkers were successfully synthesized. Their activities were evaluated in terms of binding constant K (M–1) for Cl– and reaction yield (%) in the Mukaiyama- Mannich-type reaction of isoquinoline, and the catalyst with the acetylene linker exhibited the highest activity. The significance of the two-point mode was postulated based on the X-ray diffraction analysis of the acetylene-linked halogen-bond donor with two halogen-bond donor sites. Computational studies revealed the effect of the linker on Cl– binding via halogen bonding. Finally, the utility of the acetylene- linked two-point halogen-bond donor catalyst in the Mukaiyama- Mannich-type reaction was established using various substituted isoquinolines, chloroformates, and ketene silyl acetals.