- Reaction condition controlled nickel(ii)-catalyzed C-C cross-coupling of alcohols
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The challenge in the C-C cross-coupling of secondary and primary alcohols using acceptorless dehydrogenation coupling (ADC) is the difficulty in accurately controlling product selectivities. Herein, we report a controlled approach to a diverse range of β-alkylated secondary alcohols, α-alkylated ketones and α,β-unsaturated ketones using the ADC methodology employing a Ni(ii) 4,6-dimethylpyrimidine-2-thiolate cluster catalyst under different reaction conditions. This catalyst could tolerate a wide range of substrates and exhibited a high activity for the annulation reaction of secondary alcohols with 2-aminobenzyl alcohols to yield quinolines. This work is an example of precise chemoselectivity control by careful choice of reaction conditions.
- Zhang, Meng-Juan,Li, Hong-Xi,Young, David J.,Li, Hai-Yan,Lang, Jian-Ping
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supporting information
p. 3567 - 3574
(2019/04/14)
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- Enantioselective Ring Opening of meso-Epoxides with Silicon Tetrachloride Catalyzed by Pyridine N-Oxides Fused with the Bicyclo[3.3.1]nonane Framework
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The synthesis of new chiral Lewis basic organocatalysts that contain pyridine N-oxide moieties fused with the bicyclo[3.3.1]nonane framework is reported. The obtained pyridine N-oxides were employed as catalysts in the enantioselective ring opening of meso-epoxides with silicon tetrachloride. Derivative 1b endowed with two 2,4-diaryl-substituted pyridine N-oxide moieties proved to be a particularly effective catalyst for desymmetrization of norbornene oxide 16i to furnish Wagner-Meerwein rearrangement product 20i in unprecedented 96 % ee. Difunctional congener 3, which is striped of the 4-aryl substituents, exhibited moderate to high levels of asymmetric induction (47-88 % ee) with alicyclic epoxide substrates. Chiral Lewis basic catalysts with pyridine N-oxide moieties fused with a bicyclo[3.3.1]nonane framework were used in the enantioselective ring opening of meso-epoxides. 2,4-Diaryl-substituted N-oxide exhibited excellent asymmetric induction with norbornene oxide (96 % ee), whereas less-substituted congener was most effective with alicyclic epoxide substrates (47-88 % ee).
- Neni?kis, Algirdas,Ston?ius, Sigitas
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p. 6359 - 6369
(2015/10/06)
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- Zinc oxide as a regioselective and heterogeneous catalyst for the synthesis of chalcones at room temperature
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Zinc oxide catalyzed synthesis of chalcones has been carried out under solvent-free conditions at room temperature. Activated as well as unactivated aromatics smoothly underwent Friedel-Crafts acylation with α, β-unsaturated acid chlorides furnishing excellent yields of the corresponding chalcones. The zinc oxide can be recovered and reused at least three times without any appreciable loss in activity.
- More, Parmeshwar E.,Bandgar, Babasaheb P.,Kamble, Vinod T.
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- Chiral bidentate phosphabenzene-based ligands: Synthesis, coordination chemistry, and application in Rh-catalyzed asymmetric hydrogenations
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Novel hydroxy-functionalized phosphabenzenes were synthesized, which provide the possibility to prepare chiral phosphabenzene-phosphites. These systems act as bidentate ligands toward rhodium centers and the corresponding metal complexes were applied in t
- Müller, Christian,López, Leire Guarrotxena,Kooijman, Huub,Spek, Anthony L.,Vogt, Dieter
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p. 2017 - 2020
(2007/10/03)
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- Stereoselective synthesis of enones from the reaction of aldehydes with sterically hindered dimethylaluminum enolates
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The equimolar reaction between Me3Al and the methyl ketones (2,4,6-R3-C6H2)C(O)CH3, where R = Me or iPr, results in exclusive formation of the enolization products [{Me2AlOC(2,4,6-R3-C6H2)CH 2}2], 1 and 2, upon heating to reflux temperature in toluene solution. The property of Me3Al acting as a base rather than a nucleophile in these reactions is due to the sterically hindered nature of the ketones. Crystallographic analysis of 2 revealed a dimeric complex where the metal centers are bridged by the enolate anions, consistent with the previous studies of 1. Addition of a series of aldehydes to hexane solutions of 1 and 2, followed by heating to reflux for several hours gave enone products in generally high conversions. The presumed aluminum aldolate intermediates were not detected by in situ monitoring studies and are presumably short-lived under the reaction conditions. The enone products from the addition reactions were formed predominantly as the E-isomers with good to excellent stereoselectivities.
- Sales, Zachary S.,Nassar, Roger,Morris, J. Jacob,Henderson, Kenneth W.
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p. 3474 - 3478
(2007/10/03)
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- CONJUGATE ADDITION OF GRIGNARD REAGENTS TO UNSATURATED KETONES: GC/MS-HPLC STUDY. ISOLATION AND OXIDATION OF E AND Z ENOLS OF A KETONE
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The conjugate addition of phenylmagnesium bromide to benzalacetomesitylene (1) was studied.The only product resulting from 1,4-addition was Kohler's ketone (4) in 84+/-1 percent yield based on (1) by isolation and analysis.The byproducts from 4 were forme
- Pinkus, A. G.,Logaraj, S.
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p. 6801 - 6806
(2007/10/02)
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- Carboxylic Trifluoromethanesulfonic Anhydrides as Highly Effective Acylation Agents. - Perfluoroalkanesulfonic Acid Catalyzed Acylation of Arenes
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Arene- and alkanecarboxylic trifluoromethanesulfonic anhydrides 2 and 5 are highly effective acylation agents, which react without Friedel-Crafts catalysts even with deactivated aromatics to yield aryl ketones 3 and 6, respectively.Acylation of arenes with carbonyl chlorides 4 and catalytic amounts of perfluoroalkanesulfonic acid gives ketones 3 and 6, resp., in good yields.Under similar conditions other strong Broensted acids show a considerably smaller degree of catalytic effect.
- Effenberger, Franz,Sohn, Erich,Epple, Gerhard
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p. 1195 - 1208
(2007/10/02)
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