Synthesis of di(Imdazolium) and di(Pyrazolium) Salts as Precursors for N-heterocyclic Dicarbene Complexes
| Parent link: | Procedia Chemistry Vol. 10 : Chemistry and Chemical Engineering in XXI century.— 2014.— [P. 485-489] |
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| Príomhchruthaitheoir: | |
| Rannpháirtithe: | , |
| Achoimre: | Title screen Alpha,omega-bis(pyrazol-1-yl)alkanes and alpha,omega-bis(imidazol-1-yl)alkanes with spacers consisting of four to ten methylene groups have been prepared from pyrazole, 3,5-dimethylpyrazole or imidazole and corresponding dibromoalkanes in a superbasic medium KOH-DMSO. The proposed method of synthesis allowed the preparation of new flexible bidentate ligands without the need to use toxic solvents and tedious workup procedures. Bis(pyrazol-1-yl)alkanes were further functionalized for their use as precursors for “non-classical” mesoionic N-heterocyclic carbene ligands. One the first step, iodine atoms were introduced to positions 4 of pyrazole rings by oxidative iodination using I[2]-HIO[3] system. On the next step, nitrogen atoms in positions 2 of pyrazole rings were alkylated using several agents. Reaction with methyliodide unexpectedly led to the formation of only mono-alkylated products even after 7 days of refluxing in a neat alkyliodide. Methylation by trimethyloxonium tetrafluoroborate or methyltriflate led to dimethylated products in high yields. Bis(imidazol-1-yl)alkanes were easily alkylated by methyliodide to give di(imidazolium) salts – precursors to “classic” N-heterocyclic dicarbenes. Режим доступа: по договору с организацией-держателем ресурса |
| Foilsithe / Cruthaithe: |
2014
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| Ábhair: | |
| Rochtain ar líne: | http://dx.doi.org/10.1016/j.proche.2014.10.081 http://earchive.tpu.ru/handle/11683/35535 |
| Formáid: | Leictreonach Caibidil leabhair |
| KOHA link: | https://koha.lib.tpu.ru/cgi-bin/koha/opac-detail.pl?biblionumber=639552 |