Catalyst For Diels-Alder Reaction Research Articles

Chalcones, a Privileged Scaffold: Highly Versatile Molecules in [4+2] Cycloadditions.

Chalcones are aromatic ketones found in nature as the central core of many biological compounds. They have a wide range of biological activity and are biogenetic precursors of other important molecules such as flavonoids. Their pharmacological relevance makes them a privileged scaffold, advantageous for seeking alternative therapies in medicinal chemistry. Due to their structural diversity and ease of synthesis, they are often employed as building blocks for chemical transformations. Chalcones have a carbonyl conjugated system with two electrophilic centers that are commonly used for nucleophilic additions, as described in numerous articles. They can also participate in Diels-Alder reactions, which are [4+2] cycloadditions between a diene and a dienophile. This microreview presents a chronological survey of studies on chalcones as dienes and dienophiles in Diels-Alder cycloadditions. Although these reactions occur in nature, isolation of chalcones from plants yields very small quantities. Contrarily, synthesis leads to large quantities at a low cost. Hence, novel methodologies have been developed for [4+2] cycloadditions, with chalcones serving as a 2π or 4π electron system.

An Active Catalyst for Diels-Alder Reaction of Indol with o-Benzoquinone

An Active Catalyst for Diels-Alder Reaction of Indol with o-Benzoquinone

Niobium(V) Chloride as Catalyst in Diels-Alder Reaction of Furan Ring

According to the relevant literature, the Diels-Alder reaction of furan without a catalyst can last several weeks and shows a low yield due to the diene's low reactivity. The use of Lewis acid catalysts or high pressures is described as an effective method for improving the reaction yields. This paper describes our recent study on the use of niobium pentachloride as the catalyst in Diels-Alder reactions between furan and several reactive dienophiles, among which methyl acrylate showed good yields, especially at lower temperatures. Other dienophiles have shown lower yields because of problems such as byproduct formation and the high reversibility of the reaction.

ChemInform Abstract: Ytterbium Trichloride-Catalyzed Diels-Alder Reactions of Unactivated Dienes.

Abstract Ytterbium chloride (YbCl3) is an effective and reusable catalyst for Diels-Alder reactions of unactivated dienes with α,β-unsaturated ketones and aldehydes at room temperature, leading to products with high regio- and stereoselectivities.

Formal Synthesis of 3-Deoxy-D-manno-2-Octulosonic Acid (KDO) via a Highly Double-Stereoselective Hetero Diels-Alder Reaction Directed by a (Salen)Co(II) Catalyst and Chiral Diene.

This paper presents a formal total synthesis of 3-deoxy-D-manno-2-octulosonic acid (KDO) based on a highly double-stereoselective hetero Diels-Alder reaction between an electron-rich diene and ethyl glyoxylate catalyzed by (Salen)Co(II) complex, a new catalyst for Diels-Alder reactions. A facial specific hydroboration followed by oxidative workup leads to a diol system with the trans-diequatorial arrangement of hydroxyl groups at the C-4 and C-5. Inversion of the configuration of the C-5 hydroxyl group in 12 and then ketal formation afford the desired target diisopropylidene-2-deoxy-KDO methyl ester (18), which can be converted to KDO according to the literature procedure.

Importance of chiral activators in the asymmetric catalysis of Diels-Alder reactions by chiral titanium(IV) complexes

Asymmetric activation of chiral titanium(IV) complexes is found to be essential to provide higher levels of enantioselectivity than that attained by enantiopure catalysts in Diels-Alder reactions of the Danishefsky diene and glyoxylate.

Chiral lewis acids supported on silica gel and alumina, and their use as catalysts in Diels-Alder reactions of methacrolein and bromoacrolein

Several derivatives of ( S)-tyrosine are supported on silica gel through the phenolic oxygen atom. The Lewis acids obtained by treatment of these solids with BH 3 are able to promote the reactions of methacrolein and bromoacrolein with cyclopentadiene, but they do not provide asymmetric induction. ( S)-Prolinol is supported on silica gel and alumina through the nitrogen atom, and the solids obtained by treatment with AlEtCl 2 catalyse the reaction between methacrolein and cyclopentadiene, leading to 8% enantiomeric excess (ee). The best results in these reactions (until 31% ee) are obtained by using (−)-menthol-aluminium Lewis acids supported on silica gel and alumina through the aluminium atom. The supported catalysts are compared with the analogous homogeneous Lewis acids.

Silica and alumina modified by Lewis acids as catalysts in Diels-Alder reactions of carbonyl-containing dienophiles

Several aluminium and titanium derivatives are supported on silica and alumina. Some of the solids obtained contain strong Lewis acids sites and are efficient catalysts in Diels-Alder reactions of carbonyl-containing dienophiles. In cyclopentadiene reactions, high conversions and endo/exo selectivities are obtained in short reaction times, without excess of diene and with a small amount of catalyst at room temperature. With less reactive dienes, temperature, diene proportion and reaction times must be increased. However, high regio and endo/exo selectivities are obtained. The catalyst obtained by treatment of silica with diethyl aluminium chloride retains a great deal of its catalytic activity when recovered or stored in the open air for one month.

Silica and alumina modified by Lewis acids as catalysts in Diels-Alder reactions of chiral acrylates

Silica and alumina, modified by treatment with AlClEt 2 and TiCl 4, are tested as catalysts in the reactions of cyclopentadiene ( 1) with (-)-menthyl acrylate ( 2a), (R)-O-acryloyl pantolactone ( 2b) and (S)-O-acryloyl lactate ( 2c). Silica-modified systems are the most efficient heterogeneous catalysts described to date for this kind of reaction, leading to selectivities similar to those obtained with aluminium homogeneous catalysts. Whereas silica· AlClEt 2 is better for the reaction of 2a and 2c, silica· TiCl 4 is more suitable for the reaction of 2b.

Polymer-supported Ti and Al Lewis acids as catalysts in Diels-Alder reactions

Different polymer-supported Ti and Al Lewis acid catalysts have been prepared. All of them show an appreciable catalytic activity for the reaction between methacrolein and cyclopentadiene. The exo/endo selectivity is increased relative to the uncatalyzed reaction and is slightly higher for supported Al Lewis acids. Recycling of the polymers has been studied. In general, polymer-bound Ti catalysts seem to be more effective in terms of activity and recycling.

ChemInform Abstract: TRANSITION METAL COMPLEXES AS CATALYSTS IN DIELS‐ALDER REACTIONS

Chemischer InformationsdienstVolume 14, Issue 44 Preparative Organic Chemistry ChemInform Abstract: TRANSITION METAL COMPLEXES AS CATALYSTS IN DIELS-ALDER REACTIONS M. S. BAILEY, M. S. BAILEYSearch for more papers by this authorB. J. BRISDON, B. J. BRISDONSearch for more papers by this authorD. W. BROWN, D. W. BROWNSearch for more papers by this authorK. M. STARK, K. M. STARKSearch for more papers by this author M. S. BAILEY, M. S. BAILEYSearch for more papers by this authorB. J. BRISDON, B. J. BRISDONSearch for more papers by this authorD. W. BROWN, D. W. BROWNSearch for more papers by this authorK. M. STARK, K. M. STARKSearch for more papers by this author First published: November 1, 1983 https://doi.org/10.1002/chin.198344115Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume14, Issue44November 1, 1983 RelatedInformation

Transition metal complexes as catalysts in diels-alder reactions.

Molybdenum and tungsten complexes of the type [MCl(CO) 2(η 3-allyl) (NCMe) 2] are shown to catalyse intramolecular Diels-Alder reactions. The stereochemistry of one of the cyclo-adducts is confirmed by nOe measurements at 400 MHz.