- Pd-N-heterocyclic carbene complex catalysed C-H bond activation of 2-isobutylthiazole at the C5 position with aryl bromides
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An effective and efficient catalytic system has been reported for the synthesis of C5-arylated 2-isobutylthiazoles. Pd-N-heterocyclic carbene complexes like [Pd(μ-Cl)Cl(SIPr)]2(2) and (LCl2Pd-SIPr) (3:L= PPh3,4:L= Py;5:L= 3-CHO-Py) were synthesized and characterized by1H,13C,31P NMR, LC-MS/MS, elemental analysis, and FTIR spectroscopy. These Pd-N-heterocyclic carbene complexes were assessed for the first time as catalysts for the C-H arylation reaction of 2-isobutylthiazole at the C5 position with different (hetero)aryl bromides. The catalytic system showed a low catalyst loading (1 mol%) and did not require the use of additional additives such as pivalic acid. The catalytic system developed with these catalysts enables the synthesis of fine chemicals in high yields under aerobic or anaerobic conditions. All complexes showed moderate to good yields in the C5 direct arylation of 2-isobutylthiazole, while complex2exhibited higher catalytic activity than the other complexes.
- Khan, Siraj,Bu?day, Nesrin,Ya?ar, Sedat,Ullah, Naseem,?zdemir, ?smail
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p. 6281 - 6292
(2021/04/16)
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- The p: K a values of N-aryl imidazolinium salts, their higher homologues, and formamidinium salts in dimethyl sulfoxide
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A series of imidazolinium salts, their six-, seven- A nd eight-membered homologues, and the related formamidinium salts were prepared, and their pKa values were determined in DMSO at 25 °C using the bracketing indicator method. The effect of each type of structural variation on the acidity of each salt was considered, particularly noting the importance of ring size and the effect of the steric and electronic nature of the N-aryl substituents. The effect of a cyclic structure was also probed through comparing the cyclic systems with the corresponding formamidinium salts, noting the importance of conformational flexibility in the latter cases. Along with allowing choice of appropriate bases for deprotonation of these species, it is anticipated that the data presented will aid in the understanding of the nucleophilicity, and potentially catalytic efficacy, of the corresponding carbenes.
- Cole, Marcus L.,Dunn, Michelle H.,Harper, Jason B.,Konstandaras, Nicholas,Luis, Ena T.
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p. 1910 - 1917
(2020/03/23)
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- Chromium-silicon multiple bonds: The chemistry of terminal N-heterocyclic-carbene-stabilized halosilylidyne ligands
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An efficient method for the synthesis of the first N-heterocyclic carbene (NHC)-stabilized halosilylidyne complexes is reported that starts from SiBr 4. In the first step, SiBr4 was treated with one equivalent of the N-heterocyclic c
- Filippou, Alexander C.,Chernov, Oleg,Schnakenburg, Gregor
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experimental part
p. 13574 - 13583
(2012/01/05)
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