- Montmorillonite as a heterogeneous catalyst in the efficient, mild and one pot synthesis of Schiff bases under solvent-free conditions
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A mild and efficient method has been reported for preparation of Schiff base ligands through condensation reaction of various aromatic aldehydes and ketones with different aromatic amines in the presence of montmorillonite as a heterogeneous catalyst under solvent free conditions. The advantages of this friendly, economically, environmentally and mild method are such as; simplicity of the reaction procedure, reusability of catalyst, simple work-up, high product yields and very short reaction times.
- Naeimi, Hossein,Rabiei, Khadijeh
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experimental part
p. 208 - 212
(2012/07/03)
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- Modular synthesis of indoles from imines and o-dihaloarenes or o-chlorosulfonates by a Pd-catalyzed cascade process
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A detailed study of the scope of a new Pd-catalyzed synthesis of indolesfrom 1,2-dihaloarenes and o-halobenzene sulfonates and imines is descri bed. The cascade reaction comprises an imine a-arylation ollowed by an intramolecular C-N bond-forming reaction promoted by the same Pd catalyst. The reaction with 1,2-dibromobenzene shows wide scope and allows the introduction of aryl, alkyl, and vinyl substituents at different positions of the five-membered ring of the indole. The regioselective synthesis of indoles substituted in the six-membered ring can be carried out by employing o-dihalobenzene derivatives with two different halogens, taking advantage of the different reactivities of I, Br, and Cl in oxidative addition reactions. This paper also introduces a method for the efficient cleavage of the N-t-butyl group, thus allowing for the preparation of N-H indoles through the same methodology. Finally, the reaction with o-halosulfonates has been studied. The best substrates are o-chlorononaflates, which lead to indoles in very high yield. The reaction is particularlyappropriate for the synthesis of the challenging 6-substituted indoles. In view of the availability of o-chlorophenols, which are direct precur sors of the chlorononaflates, this reaction represents an efficient entry into indoles substituted in the six-membered ring. The concept is illustrated by the preparation of a 4,6-disubstituted indole from naturally occurring anethole.
- Barluenga, Jose,Jimenez-Aquino, Agustin,Aznar, Fernando,Valdes, Carlos
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supporting information; experimental part
p. 4031 - 4041
(2009/09/04)
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- Facile and efficient method for preparation of Schiff bases catalyzed by P2O5/SiO2 under free Solvent conditions
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A simple and convenient method for the preparation of Schiff bases is developed. In this method, the Schiff base compounds were prepared from the reaction of carbonyl compounds with primary amines. In this reaction, P 2O5/SiO2 have catalyzed the Schiff base formation in dry media under solvent-free conditions. Advantages of this method are use of an inexpensive and efficient catalyst, high yields of products, short reaction times, and simplicity of the reaction and workup.
- Naeimi, Hossein,Sharghi, Hashem,Salimi, Fariba,Rabiei, Khadijeh
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- New entries toward 3,3-difluoropiperidines
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(Chemical Equation Presented) Difluoropiperidines attract considerable interest from organic and medicinal chemists, but their synthesis is often problematic. This paper describes a new synthetic pathway toward valuable 3,3-difluoropiperidines starting fr
- Verniest, Guido,Surmont, Riccardo,Van Hende, Eva,Deweweire, Arvid,Deroose, Frederik,Thuring, Jan Willem,De Kimpe, Norbert
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p. 5458 - 5461
(2008/12/21)
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- Electrophile-induced bromocyclization of γ,δ-unsaturated ketimines to intermediate 1-pyrrolinium salts and their selective conversion into novel 5-alkoxymethyl-2-aryl-3-chloropyrroles and 2-aroylpyrroles
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N-(1-Aryl-2,2-dichloropent-4-enylidene)amines were efficiently transformed into 5-bromomethyl-1-pyrrolinium bromides via electrophile-induced bromocyclization. The latter pyrrolinium salts were converted into novel 5-alkoxymethyl-2-aryl-3-chloropyrroles b
- D'Hooghe, Matthias,Buyck, Christophe,Contreras, Jan,De Kimpe, Norbert
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scheme or table
p. 3667 - 3669
(2009/02/05)
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- Direct electrophilic α-fluorination of imines: Efficient synthesis of mono-and difluoroimines
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(Chemical Equation Presented) A mild and efficient procedure to synthesize α-fluoro- and α,α-difluoroimines was developed. Various N-alkylimines derived from acetophenones were successfully monofluorinated using NFSI (N-fluorobenzenesulfonimide) in a mixture of CH3CN and DMF at 0°C. Alternatively, the same procedure without DMF gave rise to difluorinated imines when performed at room temperature. The obtained α- and α,α-difluorinated imines were subsequently reduced to give the corresponding β-fluoro- and β,β-difluoroamines in good yield.
- Verniest, Guido,Van Hende, Eva,Surmont, Riccardo,De Kimpe, Norbert
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p. 4767 - 4770
(2007/10/03)
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- Role of noncovalent interactions in the enantioselective reduction of aromatic ketimines with trichlorosilane
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Asymmetric reduction of ketimines 1 with trichlorosilane can be catalyzed by a new N-methyl L-valine derived Lewis basic organocatalyst, such as 4d, with high enantioselectivity. The structure-reactivity investigation suggests hydrogen bonding and arene-arene interactions between the catalyst and the incoming imine as the main factor determining the enantiofacial selectivity.
- Malkov, Andrei V.,Mariani, Andrea,MacDougall, Kenneth N.,Kocovsky, Pavel
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p. 2253 - 2256
(2007/10/03)
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- A simple protocol for direct reductive amination of aldehydes and ketones using potassium formate and catalytic palladium acetate
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A method for direct reductive amination of aldehydes and ketones, including α,β-unsaturated carbonyl compounds, has been developed, which requires potassium formate as reductant and palladium acetate as catalyst. Suitable amines include both primary and secondary aliphatic and aromatic amines.
- Basu, Basudeb,Jha, Satadru,Bhuiyan, Md. Mosharef H.,Das, Pralay
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p. 555 - 557
(2007/10/03)
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- Titanium dipyrrolylmethane derivatives: Rapid intermolecular alkyne hydroamination
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Alkynes are rapidly hydroaminated by primary amines using titanium dipyrrolylmethane derivatives as catalyst.
- Shi, Yanhui,Hall, Christopher,Ciszewski, James T.,Cao, Changsheng,Odom, Aaron L.
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p. 586 - 587
(2007/10/03)
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- Efficient generation of trifluoroacetaldehyde and successive reaction with imines affording β-hydroxy-β-trifluoromethyl ketones
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The reaction of trifluoroacetaldehyde ethyl hemiacetal or hydrate with an equimolar amount of imine in hexane at reflux temperature for 1 h gave the corresponding β-hydroxy-β-trifluoromethyl ketones in good to excellent yields.
- Funabiki, Kazumasa,Matsunaga, Kei,Matsui, Masaki,Shibata, Katsuyoshi
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p. 1477 - 1479
(2007/10/03)
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- An efficient, scaleable procedure for the conversion of esters to isoxazoles
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A concise, regiocontrolled route to isoxazoles, based on the condensation of an ester with a metallated imine, has been developed. The intermediate vinylogous amides react smoothly with hydroxylamine to provide, after dehydration, substituted isoxazoles. The method has been used for the multi-kilo scale preparation of ABT-418, a novel cholinergic channel activator.
- Bunnelle,Singam,Narayanan,Bradshaw,Liou
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p. 439 - 442
(2007/10/03)
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- A simple and inexpensive method for the preparation of imines and azadienes
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A number of imines and azadienes were prepared in high yield and good purity by using the condensation reactions of various aldehydes and ketones with amines over natural Algerian bentonite.
- Saoudi,Benguedach,Benhaoua
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p. 2349 - 2354
(2007/10/02)
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- Electronic and Steric Influences on Face Selection during the Oxy-Cope Rearrangement of an α-Allyl-α-vinylbenzyl Alcohol
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The racemic RR,SS and RS,SR diastereomers of 5-(5-fluoroadamant-2-ylidene)-4-hydroxy-4-phenyl-1-pentene (1-F) have been synthesized.Their configurations have been determined by means of 13C NMR as well as by way of an X-ray diffraction study of
- Lin, Man-hua,Watson, William H.,Kashyap, Ram P.,Noble, W. J. le
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p. 3597 - 3602
(2007/10/02)
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