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1
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Synthesis and characterization of some chalcones and their cyclohexenone derivatives

100%
Sreevidya T., Narayana B., Yathirajan H.
Open Chemistry
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2010
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vol. 8
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issue 1
174-181
EN
A series of chalcones and their derivatives have been synthesized. Chalcones, 1-(1,3-benzodioxol-5-yl)-3-(aryl)-prop-2-en-1-ones were prepared by the aldol condensation of 1-(1,3-benzodioxol-5-yl)ethanones and aryl aldehydes. Based-catalyzed condensation of 1-(1,3-benzodioxol-5-yl)-3-(aryl)prop-2-en-1-ones with ethyl acetoacetate yields corresponding ethyl 4-(1,3-benzodioxol-5-yl)-6-(aryl)-2-oxocyclohex-3-ene-1-carboxylates. Some of the synthesized chalcones were reported in the literature; the newly synthesized compounds were characterized by single crystal X-ray studies, IR, 1H-NMR and LCMS mass spectral analysis. [...]
2
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Poly(methylhydrosiloxane)-supported chiral thiourea-based bifunctional catalysts

88%
Puglisi A., Benaglia M., Massolo E., Celentano G.
Recyclable Catalysis
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2012
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vol. 1
1-5
EN
The design, the synthesis and the successful immobilization of a modified Takemoto's catalyst is described. As support, poly(methylhydrosiloxane (PMHS) was chosen for its several positive features: it is a cheap, commercially available polymer, easily functionalized with simple experimental procedures. The PMHS-anchored enantiomerically pure bifunctional organocatalyst was employed in the stereoselective addition of activated carbon nucleophiles to nitrostyrene and its recovery and recyclability was preliminarily investigated.
3
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Enantioselective Michael additions of aldehydes to nitroalkenes catalyzed with ionically tagged organocatalyst

88%
Šebesta R., Latika A.
Open Chemistry
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2014
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vol. 12
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issue 3
416-425
EN
Enantioselective organocatalytic Michael additions affords useful building blocks for many biologically and medicinally relevant compounds. Ionically-tagged diphenylprolinol silyl ether efficiently catalyzes several Michael additions of aldehydes to nitroalkenes in ionic liquids. The Michael additions work well in ionic liquids; yields up to 95% and enantioselectivities up to 95% ee were achieved. Furthermore, in some cases, the catalytic system was reusable.
4
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Use of (R)-Mandelic Acid as Chiral Co-Catalyst in the Michael Addition Reaction Organocatalyzed by (1S,4S)-2-Tosyl-2,5-diazabicyclo[2.2.1]heptane under Solvent-Free Conditions

75%
Ávila-Ortiz C. G., López-Ortiz M., Vega-Peñaloza A., Regla I., Juaristi E.
Asymmetric Catalysis
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2015
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vol. 2
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issue 1
EN
This article describes a study on the Michael addition reaction of cyclohexanone to nitroolefins catalyzed by the chiral secondary amine (1S,4S)-2-tosyl- 2,5-diazabicyclo[2.2.1]heptane. Reactions were carried out under solvent-free conditions to make them more environmentally friendly. Initially, the observed diastereoand enantioselectivities were moderate to good, but were significantly improved by lowering the reaction temperature. Furthermore, a variety of chiral acids were also tested as co-catalysts in both of their enantiomeric forms, which revealed that (R)-mandelic acid affords excellent results in terms of yield and stereoselectivity. Monitoring the reaction by MS-TOF allowed for the detection of key reaction intermediates, and a reasonable reaction mechanism in which both catalysts are involved is proposed.
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