Three-center-four-electron halogen bond enables non-metallic complex catalysis for Mukaiyama–Mannich-type reaction at ppm-level catalyst loading

31 March 2022, Version 2
This content is a preprint and has not undergone peer review at the time of posting.

Abstract

The three-center-four-electron halogen bond (3c4e X-bond) presents a new 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, which exhibited outstanding activity and facilitated the Mukaiyama–Mannich-type reaction of N-heteroaromatics with ppm-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 partial 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 a new application of 3c4e X-bonds for catalysis via halogen(I) complexes.

Keywords

halogen bond
three-center-four-electron bond
non-metallic complex catalysis
anion-binding catalysis
N-heteroaromatics

Supplementary materials

Title
Description
Actions
Title
Supporting Information of [N-X-N]Ys as Anion-Binding Catalyst
Description
1. General information 2. Synthesis of halogen(I) complexes 3. Synthesis of trimethylsilyl ketene acetals 4. Mukaiyama–Mannich-type reaction 5. NMR titration of [N-I-N]SbF6 with TBACl 6. CSI-MS titration of [N-I-N]SbF6 with TBACl 7. UV-vis spectra 8. Comparison of NMR spectra of [NN], [N-I-N]OTf, [NN]+HOTf 9. Scatter plots of the yield (%) vs. catalyst loading (mol%) 10. X-ray diffraction analysis of Iodonium complex 11. DFT Calculation 12. References 13. NMR spectra 14. Cartesian coordinates
Actions

Comments

Comments are not moderated before they are posted, but they can be removed by the site moderators if they are found to be in contravention of our Commenting Policy [opens in a new tab] - please read this policy before you post. Comments should be used for scholarly discussion of the content in question. You can find more information about how to use the commenting feature here [opens in a new tab] .
This site is protected by reCAPTCHA and the Google Privacy Policy [opens in a new tab] and Terms of Service [opens in a new tab] apply.