- Straight Access to Indoles from Anilines and Ethylene Glycol by Heterogeneous Acceptorless Dehydrogenative Condensation
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The development of original strategies for the preparation of indole derivatives is a major goal in drug design. Herein, we report the first straight access to indoles from anilines and ethylene glycol by heterogeneous catalysis, based on an acceptorless dehydrogenative condensation, under noninert conditions. In order to achieve high selectivity, a combination of Pt/Al2O3 and ZnO have been found to slowly dehydrogenate ethylene glycol generating, after condensation with the amine and tautomeric equilibrium, the corresponding pyrrole-ring unsubstituted indoles.
- Llabres-Campaner, Pedro Juan,Ballesteros-Garrido, Rafael,Ballesteros, Rafael,Abarca, Belén
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supporting information
p. 521 - 526
(2018/01/01)
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- β-Amino alcohols from anilines and ethylene glycol through heterogeneous Borrowing Hydrogen reaction
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Borrowing Hydrogen (BH), also called Hydrogen Autotransfer (HA), reaction with neat ethylene glycol represents a key step in the preparation of β-amino alcohols. However, due to the stability of ethylene glycol, mono-activation has rarely been achieved. Herein, a combination of Pd/C and ZnO is reported as heterogeneous catalyst for this BH/HA reaction. This system results in an extremely air and moisture stable, and economic catalyst able to mono-functionalize ethylene glycol in water, without further activation of the diol. In this work, different diols and aromatic amines have been explored affording a new approach towards amino alcohols. This study reveals how the combination of two solid species can afford interesting catalytic properties in heterogeneous phase. ZnO activates ethylene glycol while Pd/C is the responsible of the BH/HA cycle. This catalytic system has also been found useful to dehydrogenate indoles affording indolines that undergo in situ BH/HA cycle prior to re-aromatization, representing a tandem heterogeneous process.
- Llabres-Campaner, Pedro J.,Ballesteros-Garrido, Rafael,Ballesteros, Rafael,Abarca, Belén
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supporting information
p. 5552 - 5561
(2017/08/22)
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- Reaction of 1,2-difunctionalized ethanes with aryl iodides in copper-catalyzed cross-coupling: Application to synthesis of phenols
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A series of 1,2-difunctionalized ethanes, such as ethylene glycol, 2-aminoethanol, 1,2-diaminoethane, 2-dimethylaminoethanol N',N'-dimethylethane-1,2-diamine, were investigated to test the reactivity with aryl iodides in the presence of copper catalysts. Under the reaction conditions, they produce the various Cheteroatom cross-coupled products. Interestingly, ethylene glycol and 2-dimethylaminoethanol afforded mainly the phenolic compounds while the others produced different cross-coupled products. Although ethylene glycol and 2-dimethylaminoethanol resulted in the same product, their behaviors in the reaction were quite different: ethylene glycol appears to mostly act as the ligand and 2-dimethylaminoethanol appears to serve as both the ligand and reactant. This finding led to a copper-catalyzed synthesis of phenols using either ethylene glycol or 2-dimethylaminoethanol, which can be applied to a variety of aryl iodides, providing an alternative synthetic route to phenols.
- Kim, Jihye,Battsengel, Oyunsaikhan,Liu, Yajun,Chae, Junghyun
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supporting information
p. 2833 - 2840
(2016/02/05)
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- Guilty as charged: Non-innocent behavior by a pincer ligand featuring a central cationic phosphenium donor
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The synthesis of a new pincer ligand containing a central cationic N-heterocyclic phosphenium donor is described. The electrophilic nature of this cationic ligand renders it non-innocent, and coordination of this ligand to a PtCl2 fragment leads to chloride migration from Pt to the cationic phosphorus center.
- Day, Gregory S.,Pan, Baofei,Kellenberger, Daniel L.,Foxman, Bruce M.,Thomas, Christine M.
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p. 3634 - 3636
(2011/05/02)
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- Thiadiazolidine 1-oxide systems for phosphine-free palladium-mediated catalysis
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We herein report several highly active catalyst systems with thiadiazolidine 1-oxides as ligands for palladium in the Mizoroki-Heck reaction. Excellent yields of stilbenes derived from aryl iodides and bromides have been achieved using as little as 0.00002 mol % catalyst. The ligand/palladium system can be stored as a stock solution open to air at room temperature with no observable loss of activity for a period of several months.
- Buckley, Benjamin R.,Neary, Stephen P.
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experimental part
p. 7988 - 7994
(2010/10/21)
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- Microwave-promoted mono-N-alkylation of aromatic amines in water: A new efficient and green method for an old and problematic reaction
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A greener improvement to direct mono-N-alkylation of aromatic amines by alkyl halides was achieved using microwave irradiation in water without any catalyst.
- Marzaro, Giovanni,Guiotto, Adriano,Chilin, Adriana
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supporting information; experimental part
p. 774 - 776
(2010/04/23)
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- A Novel Method for the Synthesis of Symmetrical Vicinal Tertiary and Secondary Diamines
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A variety of symmetrical vicinal tertiary and secondary diamines are readily prepared in good to excellent yields by either Grignard reaction or reduction of the glyoxal bisproducts with benzotriazole and secondary or primary amines.
- Katritzky, Alan R.,Fan, Wei-Qiang,Fu, Cong
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p. 3209 - 3213
(2007/10/02)
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