- Easy α-alkylation of ketones with alcohols through a hydrogen autotransfer process catalyzed by RuCl2(DMSO)4
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The electrophilic α-alkylation of ketones with alcohols is accomplished by a hydrogen autotransfer process catalyzed by RuCl2(DMSO)4. The reaction can produce either simple alkylated ketones or α,β-unsaturated ketones just by choosing the appropriate starting ketones (methyl ketones or bicyclic methylenic ketones, respectively), as well as quinolines (by using 2-aminobenzyl alcohol derivatives) or the corresponding alcohol derivatives by the addition of an extra equivalent of the initial alcohol. In the last case, after the above alkylation process reduction of the carbonyl compound takes place. A mechanistic study seems to indicate that the process goes through the oxidation of the alcohols with ruthenium (after a previous deprotonation) to yield the corresponding aldehyde and a ruthenium hydride intermediate. In turn, the aldehyde suffers a classical aldol reaction with the starting ketone to form the corresponding α,β-unsaturated ketone, which finally is reduced through a Michael-type addition by the aforementioned ruthenium hydride intermediate.
- Martínez, Ricardo,Ramón, Diego J.,Yus, Miguel
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- Designed pincer ligand supported Co(ii)-based catalysts for dehydrogenative activation of alcohols: Studies onN-alkylation of amines, α-alkylation of ketones and synthesis of quinolines
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Base-metal catalystsCo1,Co2andCo3were synthesized from designed pincer ligandsL1,L2andL3having NNN donor atoms respectively.Co1,Co2andCo3were characterized by IR, UV-Vis. and ESI-MS spectroscopic studies. Single crystal X-ray diffraction studies were investigated to authenticate the molecular structures ofCo1andCo3. CatalystsCo1,Co2andCo3were utilized to study the dehydrogenative activation of alcohols forN-alkylation of amines, α-alkylation of ketones and synthesis of quinolines. Under optimized reaction conditions, a broad range of substrates including alcohols, anilines and ketones were exploited. A series of control experiments forN-alkylation of amines, α-alkylation of ketones and synthesis of quinolines were examined to understand the reaction pathway. ESI-MS spectral studies were investigated to characterize cobalt-alkoxide and cobalt-hydride intermediates. Reduction of styrene by evolved hydrogen gas during the reaction was investigated to authenticate the dehydrogenative nature of the catalysts. Probable reaction pathways were proposed forN-alkylation of amines, α-alkylation of ketones and synthesis of quinolines on the basis of control experiments and detection of reaction intermediates.
- Singh, Anshu,Maji, Ankur,Joshi, Mayank,Choudhury, Angshuman R.,Ghosh, Kaushik
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p. 8567 - 8587
(2021/06/30)
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- Efficient Organoruthenium Catalysts for α-Alkylation of Ketones and Amide with Alcohols: Synthesis of Quinolines via Hydrogen Borrowing Strategy and their Mechanistic Studies
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A new family of phosphine free organometallic ruthenium(II) catalysts (Ru1–Ru4) supported by bidentate NN Schiff base ligands (L1–L4 where L1=N,N-dimethyl-4-((2-phenyl-2-(pyridin-2-ylmethyl)hydrazineylidene)methyl) aniline, L2=N,N-diethyl-4-((2-phenyl-2-(pyridin-2-ylmethyl)hydrazineylidene)methyl)aniline, L3=N,N-dimethyl-4-((2-phenyl-2-(pyridin-2-yl)hydrazineylidene)methyl)- aniline and L4=N,N-diethyl-4-((2-phenyl-2-(pyridin-2-yl)hydrazineylidene)methyl) aniline) was prepared and characterized. These half-sandwich complexes acted as catalysts for C?C bond formation and exhibited excellent performance in the dehydrogenative coupling of ketones and amides. In the synthesis of C–C bonds, alcohols were utilized as the alkylating agent. A broad range of substrates, including sterically hindered ketones and alcohols, were well tolerated under the optimized conditions (TON up to 47000 and TOF up to 11750 h?1). This ruthenium (II) catalysts were also active towards the dehydrogenative cyclization of o-amino benzyl alcohol for the formation of quinolines derivatives. Various polysubstituted quinolines were synthesized in moderate to excellent yields (TON up to 71000 and TOF up to 11830 h?1). Control experiments were carried out and the ruthenium hydride intermediate was characterized to support the reaction mechanism and a probable reaction pathway of dehydrogenative coupling for the C?C bond formation has been proposed.
- Maji, Ankur,Singh, Anshu,Singh, Neetu,Ghosh, Kaushik
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p. 3108 - 3125
(2020/05/18)
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- [Pd]-Catalyzed Intermolecular Coupling and Acid Mediated Intramolecular Cyclodehydration: One-Pot Synthesis of Indenes
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An efficient one-pot synthesis of indenes from simple starting materials is presented. This process involves a dual C–C bond formation through an intermolecular Heck coupling reaction followed by acid-mediated intramolecular cyclodehydration. The strategy
- Niharika, Pedireddi,Satyanarayana, Gedu
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supporting information
p. 971 - 979
(2018/02/22)
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- Iron-catalyzed reductive dehydroxylation of benzylic alcohols using polymethylhydrosiloxane (PMHS)
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The combination of FeCl3 and PMHS is an efficient reducing system for the selective dehydroxylation of secondary benzylic alcohols, even in the presence of carbonyls, under very mild conditions. Georg Thieme Verlag Stuttgart · New York.
- Chan, Li Yan,Lim, Jazreel Seh Kai,Kim, Sunggak
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scheme or table
p. 2862 - 2866
(2012/01/11)
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- [Ru(DMSO)4] Cl2 catalyzes the α-alkylation of ketones by alcohols
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The electrophilic α-alkylation of ketones with alcohols was accomplished by a [Ru(DMSO)4]Cl2 catalyzed process, water being the only wasted material. The reaction can be successfully governed to produce either the expected ketones or their related alcohols only by changing the reaction conditions. When 2-aminobenzyl alcohol was used, a cyclization process took place to yield 2,3-disubstituted quinolines.
- Martínez, Ricardo,Brand, Gabriel J.,Ramón, Diego J.,Yus, Miguel
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p. 3683 - 3686
(2007/10/03)
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- Synthesis and nuclear magnetic resonance spectroscopy of indane structures: indanes mono- and disubstituted in the pentagonal ring
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Indanes monosubstituted and 1,2- and 1,3-disubstituted in the pentagonal ring were synthesized, and configurations were assigned to the 1,2-disubstituted compounds by means of nuclear magnetic resonance spectroscopy.Key words: mono- and disubstituted indanes, conformation, configuration, 1H and 13C NMR, synthesis.
- Alesso, Elba N.,Tombari, Dora G.,Ibanez, Adriana F.,Iglesias, Graciela Y. Moltrasio
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p. 1166 - 1170
(2007/10/02)
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