- “Inverse” Frustrated Lewis Pairs: An Inverse FLP Approach to the Catalytic Metal Free Hydrogenation of Ketones
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For the first time have boron-containing weak Lewis acids been demonstrated to be active components of Frustrated Lewis Pair (FLP) catalysts in the hydrogenation of ketones to alcohols. Combining the organosuperbase (pyrr)3P=NtBu with the Lewis acid 9-(4-CF3-C6H4)-BBN generated an “inverse” FLP catalyst capable of hydrogenating a range of aliphatic and aromatic ketones including N-, O- and S-functionalized substrates and bio-mass derived ethyl levulinate. Initial computational and experimental studies indicate the mechanism of catalytic hydrogenation with “inverse” FLPs to be different from conventional FLP catalysts that contain strong Lewis acids such as B(C6F5)3.
- Mummadi, Suresh,Brar, Amandeep,Wang, Guoqiang,Kenefake, Dustin,Diaz, Rony,Unruh, Daniel K.,Li, Shuhua,Krempner, Clemens
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supporting information
p. 16526 - 16531
(2018/10/20)
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- A Highly Active and Easily Accessible Cobalt Catalyst for Selective Hydrogenation of C=O Bonds
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The substitution of high-price noble metals such as Ir, Ru, Rh, Pd, and Pt by earth-abundant, inexpensive metals like Co is an attractive goal in (homogeneous) catalysis. Only two examples of Co catalysts, showing efficient C=O bond hydrogenation rates, are described. Here, we report on a novel, easy-to-synthesize Co catalyst family. Catalyst activation takes place via addition of 2 equiv of a metal base to the cobalt dichlorido precatalysts. Aldehydes and ketones of different types (dialkyl, aryl-alkyl, diaryl) are hydrogenated quantitatively under mild conditions partially with catalyst loadings as low as 0.25 mol%. A comparison of the most active Co catalyst with an Ir catalyst stabilized by the same ligand indicates the superiority of Co. Unique selectivity toward C=O bonds in the presence of C=C bonds has been observed. This selectivity is opposite to that of existing Co catalysts and surprising because of the directing influence of a hydroxyl group in C=C bond hydrogenation.
- R?sler, Sina,Obenauf, Johannes,Kempe, Rhett
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supporting information
p. 7998 - 8001
(2015/07/08)
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- Oxidation of a anticholinergic drug atropine sulfate monohydrate by alkaline copper(III) periodate complex: A kinetic and mechanistic study
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The oxidation of a anticholinergic drug, Atropine sulfate monohydrate (ASM) by diperiodatocuprate( III) (DPC) has been investigated spectrophotometrically in aqueous alkaline medium at a constant ionic strength of 0.50mol dm -3. The reaction between diperiodatocuprate(III) and atropine sulfate exhibits 1 : 2 stoichiometry (atropine sulfate : diperiodatocuprate(III)). The main oxidation products were identified and confirmed by spectral studies including IR, 1H NMR and GC-MS. A suitable mechanism is proposed. The order with respect to diperiodatocuprate(III) concentration was unity, while the order with respect to atropine sulfate concentration was less than unity over the concentration range studied. The rates increased with an increase in alkali concentration and decreased with an increase in periodate concentration. The activation parameters with respect to slow step of the mechanism were calculated and the thermodynamic quantities were also determined. Kinetic experiments suggest that [Cu(OH)2(H3IO6)]- is the reactive species of copper(III). by Oldenbourg Wissenschaftsverlag, Muenchen.
- Byadagi, Kirthi S.,Hosahalli, Rajeshwari V.,Nandibewoor, Sharanappa T.,Chimatadar, Shivamurti A.
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p. 233 - 249
(2012/06/04)
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- Synthesis of a new series of 2,7-diazaspirononan-1-ones and study of their cholinergic properties
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A new series of substituted 2,7-diazaspirononan-1-ones (1a-l), structurally related to the muscarinic agonist RS-86, has been synthesized and tested for cholinergic properties both in vitro and in vivo.None of the compounds showed significant cholinergic properties at either the central or peripheral level.A possible explanation for the lack of activity is given.Alzheimer's disease / cholinergic system / RS-86 / muscarinic agonists
- Cignarella, G.,Villa, S.,Barlocco, D.
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p. 115 - 120
(2007/10/02)
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- ALKALOIDS OF Convolvulus subhirsutus
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The total alkaloids of the roots of Convolvulus subhirsutus collected in the period of vigorous growth close to the village of Dzhilga, Chimkent province, have been studied.From the phenolic fraction of the total alkaloids of this species of plant we have isolated phyllalbine and convolidine for the first time.From the nonphenolic fraction of the combined bases we isolated convolvine, which has been found previously, the new alkaloid confoline, and an unidentified base (III).On the basis of spectral characteristics and some spectral transformations it has been established that confoline has the structure of (+)-N-formylconvolvine.
- Sharova, E. G.,Aripova, S. F.,Yunusov, S. Yu.
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p. 487 - 490
(2007/10/02)
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