Catalysis

Three-center-four-electron halogen bond enables non-metallic complex catalysis for Mukaiyama–Mannich-type reaction

Authors

  • Shunya OISHI Institute for Molecular Science & The Graduate University for Advanced Studies, SOKENDAI ,
  • Takeshi FUJINAMI Institute for Molecular Science ,
  • Yu MASUI Institute for Molecular Science & The Graduate University for Advanced Studies, SOKENDAI ,
  • Toshiyasu SUZUKI Institute for Molecular Science ,
  • Masayuki KATO Institute for Molecular Science & The Graduate University for Advanced Studies, SOKENDAI ,
  • Naoya OHTSUKA Institute for Molecular Science & The Graduate University for Advanced Studies, SOKENDAI ,
  • Norie MOMIYAMA Institute for Molecular Science & The Graduate University for Advanced Studies, SOKENDAI

Abstract

The three-center-four-electron halogen bond (3c4e X-bond) presents a fundamental design concept for catalysis. By integrating halogen(I) (X+: I+ or Br+), bis-pyridyl ligand NN, and non- nucleophilic counter anion Y, we developed non-metallic complex catalysts, [N···X···N]Ys, that exhibited outstanding activity and facilitated the Mukaiyama–Mannich-type reaction of N- heteroaromatics with parts-per-million-level catalyst loading. The high activity of [N···X···N]SbF6 was clearly demonstrated. NMR titration experiments, CSI-MS, computations, and UV-vis spectroscopic studies suggest that the robust catalytic activity of [N···X···N]Y can be attributed to the unique feature of the 3c4e X-bond for binding chloride: i) the covalent nature transforms [N···X···N]+ complexation to sp2CH as a hydrogen bonding donor site, and ii) the noncovalent property allows for the dissociation of [N···X···N]+ for the formation of [Cl···X···Cl]–. This study introduces the application of 3c4e X-bonds for catalysis via halogen(I) complexes.

Version notes

According to the reviewer's comments, we made revisions. Furthermore, the manuscript format was really organized based on the target journal.

Content

Thumbnail image of 22-08 SO_TF [N-X-N]Ys 220808 ChemRxiv All.pdf

Supplementary material

Thumbnail image of 22-08 SO_TF [N-X-N]Ys 220808 ChemRxiv SI.pdf
Supporting Information of [N-X-N]Ys as Anion-Binding Catalyst
1. Synthesis of halogen(I) complexes 2. Synthesis of trimethylsilyl ketene acetals 3. Mukaiyama–Mannich-type reaction 4. NMR titration of [N-I-N]SbF6 with TBACl 5. CSI-MS titration of [N-I-N]SbF6 with TBACl 6. UV-vis spectra 7. Comparison of NMR spectra of [NN], [N-I-N]OTf, [NN]+HOTf 8. Scatter plots of the yield (%) vs. catalyst loading (mol%) 9. X-ray diffraction analysis of Iodonium complex 10. DFT Calculation 11. References 12. NMR spectra 13. Cartesian coordinates