Knoevenagel condensation catalysed by aluminium oxide.

Texier‐Boullet, Françoise; Foucaud, A.

doi:10.1016/s0040-4039(00)85749-4

Cited by 240 publications

(77 citation statements)

References 10 publications

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“…After the reaction was cooled down, the product was extracted with dichloromethane (2 ¥ 20 ml). 19 The solvent was then removed, leaving a product with appropriate purity. Olefin cyclohepta-2,4,6-trienylidene malononitrile (1k) was prepared via the following method:…”

Section: Gc-ms Was Measured On a Varian 450 Gc (Saturn 2000 Gc-ms/ms)mentioning

confidence: 99%

Synthetic and mechanistic studies of metal-free transfer hydrogenations applying polarized olefins as hydrogen acceptors and amine borane adducts as hydrogen donors

2012

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Metal-free transfer hydrogenation of polarized olefins (RR'C=CEE': R, R' = H or organyl, E, E' = CN or CO(2)Me) using amine borane adducts RR'NH-BH(3) (R = R' = H, AB; R = Me, R' = H, MAB; R = (t)Bu, R' = H, tBAB; R = R' = Me, DMAB) as hydrogen donors, were studied by means of in situ NMR spectroscopy. Deuterium kinetic isotope effects and the traced hydroboration intermediate revealed that the double H transfer process occurred regio-specifically in two steps with hydride before proton transfer characteristics. Studies on substituent effects and Hammett correlation indicated that the rate determining step of the H(N) transfer is in agreement with a concerted transition state. The very reactive intermediate NH(2)=BH(2)] generated from AB was trapped by addition of cyclohexene into the reaction mixture forming Cy(2)BNH(2). The final product borazine (BHNH)(3) is assumed to be formed by dehydrocoupling of NH(2)=BH(2)] or its solvent stabilized derivative NH(2)=BH(2)]-(solvent), rather than by dehydrogenation of cyclotriborazane (BH(2)NH(2))(3) which is the trimerization product of NH (2) Metal-free transfer hydrogenation of polarized olefins (RR¢C CEE¢: R, R¢ = H or organyl, E, E¢ = CN or CO 2 Me) using amine borane adducts RR¢NH-BH 3 (R = R¢ = H, AB; R = Me, R¢ = H, MAB; R = t Bu, R¢ = H, tBAB; R = R¢ = Me, DMAB) as hydrogen donors, were studied by means of in situ NMR spectroscopy. Deuterium kinetic isotope effects and the traced hydroboration intermediate revealed that the double H transfer process occurred regio-specifically in two steps with hydride before proton transfer characteristics. Studies on substituent effects and Hammett correlation indicated that the rate determining step of the H N transfer is in agreement with a concerted transition state.

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Section: Gc-ms Was Measured On a Varian 450 Gc (Saturn 2000 Gc-ms/ms)mentioning

confidence: 99%

Synthetic and mechanistic studies of metal-free transfer hydrogenations applying polarized olefins as hydrogen acceptors and amine borane adducts as hydrogen donors

2012

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“…This condensation may be carried out in various homogeneous media using catalysts such as piperidine [1,2], amines, ammonia, and ammonium salts [3][4][5]. In recent years much attention has been focused to use of natural inorganic solids such as alumina [6,7], amino groups immobilized on silica gel [8], zinc, magnesium and aluminum oxides [9][10][11][12], resins [13] magnesium phosphate [14,15] and natural phosphate impregnated with sodium nitrate [16] to catalyze organic reactions in heterogeneous media.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Substituted Stilbenes via the Knoevenagel Condensation

Al‐Shihry¹

2004

Molecules

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Knoevenagel condensations between aldehydes and substrates containing active methylene groups were carried out in ethanol at room temperature, in the presence of potassium phosphate, to afford unsymmetrical olefins. These condensations have been shown to afford only the E-isomers in greater than 80% yields. Salicylaldehyde first produces the Knoevenagel condensation products, which undergo a subsequent heterocyclization to give coumarin derivatives. The structures of the synthesized compounds were established on the basis of UV, IR, MS and NMR spectroscopy.

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“…Apart from this, use of various other Lewis acid and base catalysts such as ZnCl 2 , CdI 2 , Al 2 O 3 , KF/Al 2 O 3 , MgF has been reported in the literature [22][23][24][25][26]. Further, solid phase catalyst [27], synthetic phosphates such as Na 2 CaP 2 O 7 [28], NaY zeolites [29], cesium modified mesoporous materials [30] have also been listed but still most of these suffered from significant drawbacks such as toxic reagents, organic wastes, harsh reaction conditions, low yields or long reaction times.…”

Section: Canadian Chemical Transactionsmentioning

confidence: 99%

Synthesis of Novel Pyrazolylmethylene-Pyrimidine Heterocycles: Potential Synthons for Hybrid Β-Lactams

2015

Can Chem Trans

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Diversely substituted novel pyrazolylmethylene-pyrimidine heterocycles were synthesized via Knoevenagel condensation between substituted formyl pyrazoles and barbituric acids without any base or solid catalyst. All these thirteen novel heterocycles were characterized by FT-IR, NMR spectroscopy ( 1 H, 13 C), 13 C DEPT-135, 1 H- 13C HSQC, elemental analysis and mass spectrometry (in representative case).

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Knoevenagel condensation catalysed by aluminium oxide.

Cited by 240 publications

References 10 publications

Synthetic and mechanistic studies of metal-free transfer hydrogenations applying polarized olefins as hydrogen acceptors and amine borane adducts as hydrogen donors

Synthetic and mechanistic studies of metal-free transfer hydrogenations applying polarized olefins as hydrogen acceptors and amine borane adducts as hydrogen donors

Synthesis of Substituted Stilbenes via the Knoevenagel Condensation

Synthesis of Novel Pyrazolylmethylene-Pyrimidine Heterocycles: Potential Synthons for Hybrid Β-Lactams

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