- Solvent-free chelation-assisted hydroacylation of olefin by rhodium(I) catalyst under microwave irradiation
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A solvent-free protocol for the rhodium(I)-catalyzed intermolecular hydroacylation was achieved under microwave irradiation to furnish various ketones in high yields. The reactivity was improved by the addition of aniline as well as 2-amino-3-picoline and benzoic acid to induce a transimination, which facilitates the formation of intermediate aldimine. A comparison of the reactivity between the reaction performed under the conventional heating mode and the microwave irradiation using monomode reactor revealed an important specific microwave effect during the chelation-assisted hydroacylation. It is supposed that the observed specific microwave effect mainly originates from the formation of aldimine by condensation of aldehyde and amine, which leads to a development of charges in the transition state. This result confirms that the rate-determining step of the reaction is the initial condensation step rather than the subsequent hydroiminoacylation step.
- Loupy, Andre,Chatti, Saber,Delamare, Sarah,Lee, Dae-Yon,Chung, Jong-Hwa,Jun, Chul-Ho
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- Rhodium-Catalyzed Remote Isomerization of Alkenyl Alcohols to Ketones
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We develop herein an efficient rhodium-catalyzed remote isomerization of aromatic and aliphatic alkenyl alcohols into ketones. This catalytic process, with a commercially available catalyst and ligand ([RhCl(cod)]2 and Xantphos), features high efficiency, low catalyst loading, good functional group tolerance, a broad substrate scope, and no (sub)stoichiometric additive. Preliminary mechanistic studies suggest that this transformation involves an iterative dissociative β-hydride elimination-migration insertion process.
- Dong, Wenke,Yang, Hongxuan,Yang, Wen,Zhao, Wanxiang
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- Palladium/NHC (NHC = N-Heterocyclic Carbene)-Catalyzed B-Alkyl Suzuki Cross-Coupling of Amides by Selective N-C Bond Cleavage
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A highly chemoselective, palladium-NHC (NHC = N-heterocyclic carbene)-catalyzed, direct cross-coupling between B-sp3-alkyl reagents and activated amides by N-C(O) cleavage is reported. Palladium-NHC precatalysts promote chemoselective alkylations of amides that are inaccessible by applying strong organometallic reagents. Various amides, including challenging primary amides after direct and site-selective N,N-di-Boc activation, are compatible with this method. The potential of this mild protocol is demonstrated in sequential C(sp2)-C(sp2)/C(sp2)-C(sp3) cross-couplings deploying a di-Boc amide derived from a common primary amide bond. The method provides a rare example of air- and moisture-stable, well-defined, and highly reactive Pd-NHC precatalysts in B-alkyl-Suzuki cross-couplings.
- Meng, Guangrong,Szostak, Michal
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supporting information
p. 6789 - 6793
(2018/11/21)
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- Esters as acylating reagent in a Friedel-Crafts reaction: Indium tribromide catalyzed acylation of arenes using dimethylchlorosilane
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(Chemical Equation Presented) The Friedel-Crafts acylation of arenes with esters by dimethylchlorosilane and 10 mol % of indium tribromide has been achieved. The key intermediate RCOOSi(Cl)Me2 is generated from alkoxy esters with the evolution of the corresponding alkanes. The scope of the alkoxy ester moiety was wide: tert-butyl, benzyl, allyl, and isopropyl esters were successful. In addition, we demonstrated the direct synthesis of the indanone intermediate 11 of salviasperanol from ester 10.
- Nishimoto, Yoshihiro,Babu, Srinivasarao Arulananda,Yasuda, Makoto,Baba, Akio
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supporting information; experimental part
p. 9465 - 9468
(2009/04/06)
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- In(III)-mediated chemoselective dehydrogenative interaction of ClMe 2SiH with carboxylic acids: Direct chemo- And regioselective friedel-crafts acylation of aromatic ethers
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Chemoselective dehydrogenative interaction of ClMe2SiH with a carboxylic acid group in the presence of InX3 is reported. 13C NMR investigation revealed the formation of PhCOOSi(Cl)Me 2as the major transient intermediate. Chemo- and regioselective Friedel-Crafts acylation of aromatic ethers directly from carboxylic acids was established.
- Babu, Srinivasarao Arulananda,Yasuda, Makoto,Baba, Akio
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p. 405 - 408
(2008/02/12)
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