Knoevenagel, wittig and wittig-horner reactions in the presence of magnesium oxide or zinc oxide.

Moison, H.; Texier‐Boullet, Françoise; Foucaud, A.

doi:10.1016/s0040-4020(01)89986-5

Cited by 139 publications

(43 citation statements)

References 26 publications

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“…4). In a first approximation, we attribute this increase in activity to a higher content of ZnO impurities in the former sample, since nanocrystalline ZnO has been reported to be active for the Knoevenagel condensation reaction [17,18].…”

Section: Catalytic Activity Of Mof-5mentioning

confidence: 90%

An unexpected bifunctional acid base catalysis in IRMOF-3 for Knoevenagel condensation reactions

Xamena

Cirujano

Corma

2012

Microporous and Mesoporous Materials

154

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In this work we have reexamined the catalytic properties of zinc aminoterephthalate IRMOF-3 for the Knoevenagel condensation of benzaldehyde and ethyl cyanoacetate. The active sites for this reaction were previously proposed to consist in the amino groups of the aminoterephthalate linkers [1]. We have now found that the reaction can also be catalyzed by MOF-5, which has the same crystalline structure than IRMOF-3, but in which the aminoterephthalate ligand is replaced by terephthalate, thus lacking the amino groups that are present in IRMOF-3. It has been found that the catalytic activity of MOF-5 is related with the presence of defects and/or occluded metal oxides. Different preparation routes of MOF-5 have been followed that result in different concentration of defects and different reactivity. These defects sites can also be present in IRMOF-3 and contribute to the catalytic activity. Therefore, depending on the preparation conditions and on the concentration of defects, in the case of IRMOF-3 we can pass from a simple, monofunctional base to a (unintentional) bifunctional catalyst.

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Section: Catalytic Activity Of Mof-5mentioning

confidence: 90%

An unexpected bifunctional acid base catalysis in IRMOF-3 for Knoevenagel condensation reactions

Xamena

Cirujano

Corma

2012

Microporous and Mesoporous Materials

154

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“…138) In the course of our study on Knoevenagel condensation for preparation of the requisite a-cyano-a,b-unsaturated ester, ketone, sulfone, and imide 28a-e from benzaldehyde and several a-substituted nitriles 27a-e, we discovered that bifunctional thiourea 2a could be used as an effective catalyst comparable to the standard reaction conditions. [139][140][141] In practice, the heating of nitriles 27a-e and benzaldehyde with 10 mol% of thiourea 2a for several hours provided the corresponding E-isomers 28a-e exclusively in good yields (Table 6).…”

Section: )mentioning

confidence: 99%

Development of Chiral Thiourea Catalysts and Its Application to Asymmetric Catalytic Reactions

2010

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We have developed several multifunctional thiourea catalysts bearing a tertiary amine or an 1,2-amino alcohol in expectation of their synchronous activation of a nucleophile and an electrophile through both acid-base and hydrogen-bonding interactions. From these studies, it was revealed that the weak acidity of thioureas compared with metallic Lewis acids could be overcome by this modification. The bifunctional aminothiourea could be used efficiently for a wide range of diastereoselective and enantioselective nucleophilic reactions such as Michael addition of 1,3-dicarbonyl compounds to nitroolefines, aza-Henry reaction of nitroalkanes to N-Boc imines, and hydrazination of cyclic b b-keto esters. We also discovered that multifunctional thiourea catalyst, bearing an 1,2-amino alcohol moiety, significantly accelerated the Petasis-type reaction of alkenylboronic acids to Nphenoxycarbonyl quinolinium salts, prepared from quinolines and phenyl chloroformate, to afford 1,2-addition products with high enantioselectivity (up to 97% ee). Furthermore, to expand the synthetic applicability of the thiourea-catalyzed asymmetric reactions, tandem organocatalyzed reactions were explored to establish the concise one-pot synthesis of chiral densely functionalized three-, five-, and six-membered compounds.

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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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Knoevenagel, wittig and wittig-horner reactions in the presence of magnesium oxide or zinc oxide.

Cited by 139 publications

References 26 publications

An unexpected bifunctional acid base catalysis in IRMOF-3 for Knoevenagel condensation reactions

An unexpected bifunctional acid base catalysis in IRMOF-3 for Knoevenagel condensation reactions

Development of Chiral Thiourea Catalysts and Its Application to Asymmetric Catalytic Reactions

Synthesis of Substituted Stilbenes via the Knoevenagel Condensation

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