Scalable Synthesis of 1,3,4,5-Tetraaryl Imidazolium Salts as Precursors of Sterically Demanding N-Heterocyclic Carbenes

0532451 - ÚACH 2021 RIV DE eng J - Journal Article
Azap, C. - Christoffers, A. - Kadyrov, Renat
Scalable Synthesis of 1,3,4,5-Tetraaryl Imidazolium Salts as Precursors of Sterically Demanding N-Heterocyclic Carbenes.
SynOpen. Roč. 4, č. 1 (2020), s. 1-11. ISSN 2509-9396
Institutional support: RVO:61388980
Keywords : nucleophilic carbenes * ruthenium catalysts * ligands * carbene ligands * heterocycles * imidazolium salts * imidazolin-thiones * thioureas
OECD category: Inorganic and nuclear chemistry
Method of publishing: Open access

A convenient, large-scale, and cost-efficient synthesis of 4,5-diarylsubstituted N , Ndiarylimidazolium salts is described. A variety of 1,3,4,5-tetraaryl imidazolium salts with increasing electron donation and steric bulk of the Naryl groups was synthesized in good yields. In the key step, readily available N , N '-diarylthioureas and benzoin/anisoin are coupled to give imidazole-2-thiones, followed by imidazolium salt formation by oxidative desulfurization. In this way, N , Ndiarylimidazolium salts with 2-methoxy, 2-methyl, and 2-isopropyl substituents could be obtained, the synthesis of their 2- tertbutyl, 2,6-dimethyl, and 2,6-diisopropyl analogues failed.
Permanent Link: http://hdl.handle.net/11104/0310939