87995-51-5Relevant academic research and scientific papers
Carbocation Catalyzed Bromination of Alkyl Arenes, a Chemoselective sp3 vs. sp2 C?H functionalization.
Ni, Shengjun,El Remaily, Mahmoud Abd El Aleem Ali Ali,Franzén, Johan
, p. 4197 - 4204 (2018)
The versatility of the trityl cation (TrBF4) as a highly efficient Lewis acid organocatalyst is demonstrated in a light induced benzylic brominaion of alkyl-arenes under mild conditions. The reaction was conducted at ambient temperature under common hood light (55 W fluorescent light) with catalyst loadings down to 2.0 mol% using N-bromosuccinimide (NBS) as the brominating agent. The protocol is applicable to an extensive number of substrates to give benzyl bromides in good to excellent yields. In contrast to most previously reported strategies, this protocol does not require any radical initiator or extensive heating. For electron-rich alkyl-arenes, the trityl ion catalyzed bromination could be easily switched between benzylic sp3 C?H functionalization and arene sp2 C?H functionalization by simply alternating the solvent. This chemoselective switch allows for high substrate control and easy preparation of benzyl bromides and bromoarenes, respectively. The chemoselective switch was also applied in a one-pot reaction of 1-methylnaphthalene for direct introduction of both sp3 C?Br and sp2 C?Br functionality. (Figure presented.).
Heterogeneous palladium-catalysed intramolecular C(sp3)[sbnd]H α-arylation for the green synthesis of oxindoles
Anastasiou, Ioannis,Chen, Shaomin,Ferlin, Francesco,Gu, Yanglong,Liu, Ping,Minio, Francesco,Salameh, Nihad,Santoro, Stefano,Vaccaro, Luigi
, (2022/03/27)
Herein, we present our results on the development of a waste-minimized protocol for the synthesis of oxindoles using cyclopentyl methyl ether (CPME) as a safe and green reaction medium and palladium on carbon (Pd/C) as a reusable catalyst. This protocol is efficiently applied to a variety of substrates affording products with excellent yields, minimal metal contamination and minimum waste production. The catalyst was recovered and reused for four consecutive runs without any apparent loss of efficiency. Moreover, products were isolated by simple precipitation from heptane with no need for chromatographic separations, and both CPME and heptane were recovered. Waste-minimization is reflected by the low E-factor calculated for the presented protocol.
Thermolysis and radiofluorination of diaryliodonium salts derived from anilines
Linstad, Ethan J.,Vāvere, Amy L.,Hu, Bao,Kempinger, Jayson J.,Snyder, Scott E.,DiMagno, Stephen G.
supporting information, p. 2246 - 2252 (2017/03/17)
Aniline-derived diaryliodonium salts were synthesized and functionalized in good to excellent yields by judicious utilization of electron-withdrawing protecting groups. This simple approach opens another route to radiolabeling amino arenes in relatively complex molecules, such as flutemetamol.
Carbanionically Induced -Migrations of ?- and Coordinatively Unsaturated Groups
Hellwinkel, Dieter,Laemmerzahl, Frank,Hofmann, Gunter
, p. 3375 - 3405 (2007/10/02)
According to a general reaction scheme, o-lithioaryl esters 4a,b, amides 13a,b 17b, and amidines 39b of non-enolizable carboxylic acids as well as a corresponding diphenylphosphinic amide 51b react under mild conditions to give the intensely coloured lithium derivatives of o-acylphenoles 6a,b and o-acylarenamines 15a,b, 18a, 41a, 52a, which are finally hydrolyzed to the neutral products 7a,b, 14a,b, 18b, 41b, 52b, respectively.The lithiated precursors of the rearrangement are mostly prepared by halogen/metal exchange reactions.In the case of N,N-di-p-tolylpivalamide 33 such a -rearrangement also could be induced by direct metalation of the educt.With N-methyl-N-phenylpivalamide (29), however, exclusive metalation of the N-methyl group occurs, followed by -migration of the pivaloyl group.Silyl groups, too, can undergo analogous -shifts, as was demonstrated by the rearrangement of the o-lithiated N-(trimethylsilyl)aniline 63b to the o-(trimethylsilyl)anilines 65a,b.When a benzoyl and sulfonyl group can compete for the -shifts, as in the N-tosylated benzamide 47b, only the benzoyl group migrates.However, the migration tendency of the trimethylsilyl group equals that of the benzoyl group as was shown with the N-silylated benzamide 66b.
