Ammonium skeletal editing
The ammonium skeleton, which has cationic charge on the nitrogen atom, is include in many important molecules such as bioactive molecules, surfactants, and organocatalysts due to its unique physical properties. However, at present, there are only a limited number of methods for synthesizing ammonium compounds, and the chemical space of the ammonium skeleton has not been fully exploited. In our laboratory, we will solve this problem by establishing editing methods of ammonium skeletons and pursue new science pioneered by ammonium molecules.
<Distonic radical project>
Distonic radicals are active species in which the radical and ionic sites are separated via bonding. Although interesting reactivity is expected due to their ionic properties, research focusing on this active species has remained unexplored. Therefore, we have developed a new method for photocatalytic generation of α-ammonio radicals, a type of dystonic radicals. We found that the synthesis of ammonium salts by this method is possible through a completely different route than conventional methods, and that the synthesized ammonium compounds have a new biological activity, salt tolerance.
"Switchable quaternary ammonium transformation leading to salinity-tolerance-conferring plant biostimulants"
Takumi Kinoshita, Yota Sakakibara, Tomoko Hirano*, Kei Murakami*
ChemRxiv 2023, DOI:10.26434/chemrxiv-2023-bwm63
[Related work]
"Switchable Decarboxylation by Energy- or Electron-Transfer Photocatalysis"
Yota Sakakibara, Kenichiro Itami, and Kei Murakami*
J. Am. Chem. Soc. 2024, 146, 1554–1562. DOI:10.1021/jacs.3c11588
"Switchable Divergent Synthesis Using Photocatalysis"
Yota Sakakibara, Kei Murakami*
ACS Catal. 2022, 12, 1857–1878. DOI/10.1021/acscatal.1c05318
<Structurally new ammonium project>
Despite the structures of quaternary ammonium salts being incorporated into a variety of important molecules, their synthetic methods rely on classical nucleophilic substitution reactions. As a result, there are still countless ammonium salts that are difficult to synthesize. Therefore, we have been investigating the synthesis of ammonium salts based on the approach of “ammonium skeletal transformation”. We have established a new group of ammonium compounds, α-regioselective alkenylammonium salts, by utilizing transition metal catalysts.
"Synthesis of α-substituted alkenylammonium salts through Suzuki–Miyaura and Sonogashira coupling"
Aoi Yoshita, Yota Sakakibara, Kei Murakami*
Bull. Chem. Soc. Jpn. 2023, 96, 303–305. DOI:10.1246/bcsj.20230018