Asymmetric Diels-Alder Reaction Of Cyclopentadiene Research Articles

DABCO-based chiral ionic liquids as recoverable and reusable organocatalyst for asymmetric Diels-Alder reaction.

New DABCO-based chiral ionic liquids were synthesized and evaluated in asymmetric Diels-Alder reaction of cyclopentadiene with α,β-unsaturated aldehydes or 4-phenyl-3-buten-2-one. Chiral ionic liquid of modified MacMillan catalyst having a DABCO cation and hexafluorophosphate anion acts as organocatalyst (5mol%) for the Diels-Alder reaction of crotonaldehyde and cyclopentadiene producing 98% of the product and 87% ee (endo) in CH3 CN/H2 O (95/5) at 25°C in 2h. The scope and limitations of the catalysis were also studied by using cyclopentadiene and α,β-unsaturated aldehydes, and the Diels-Alder products were obtained in 18%-92% yields with 68%-93% ee. The catalyst was recycled and reused up to 6 cycles with a slight drop in ee and conversion of the product.

Oxathiaborolium: A Type of Chiral Lewis Acid Catalyst and Its Application in Catalytic and Highly Enantioselective Diels-Alder Reactions.

The first reported sulfur-stabilized borenium cations were synthesized through halide abstraction of a haloborane intermediate by halophilic reagents. Different from the well-known cationic oxazaborolidines, a sulfide instead of an amine was used to not only simplify the preparation of the catalysts but also increase Lewis acidity of the boron atom. The in situ generated borenium salts showed exceptional Lewis acidity and successfully catalyzed asymmetric Diels-Alder reactions of cyclopentadiene and dienophiles in excellent yields and enantioselectivities. The NMR studies of these oxathiaborolium structures were reported as well.

ChemInform Abstract: Asymmetric Diels-Alder Reaction of Cyclopentadiene and Methyl Acrylate Catalyzed by Chiral Lewis Acids.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Asymmetric Diels-Alder reactions of cyclopentadiene in the synthesis of chiral norbornene derivatives

The review discusses available data on asymmetric Diels-Alder reactions of cyclopentadiene, which were published in the past decade. Both noncatalytic and catalytic (in the presence of achiral and chiral catalysts) versions of these reactions are considered. Effects of various factors on the chemical and optical yields, stereoselectivity, and optical purity of the Diels-Alder adducts are analyzed. Prospects in the development of this field of organic chemistry are examined.

Optically active 1,2-bis(1-arylhydroxymethyl) ferrocene: a new, efficient chiral ligand for scandium-catalyzed asymmetric Diels-Alder reaction.

[reaction: see text] The Sc(OTf)3/FERRODIOL (2) complex was prepared at -78 degrees C in CH2Cl2 in the presence of 2,6-lutidine and MS 4A. The chiral scandium Lewis acid-catalyzed asymmetric Diels-Alder reaction of cyclopentadiene (3) with 3-acyloxazolidin-2-ones (4) effectively produced the adduct (5) in a high yield with good selectivity, i.e., endo/exo = 90:10 up to 91% ee (endo).

Rare Earth Salt Catalyzed Asymmetric Diels-Alder Reaction with a Chiral Dienophile in Supercritical Carbon Dioxide: Enhancement Effect on Stereoselectivity

The rare earth(III) salt catalyzed asymmetric Diels-Alder reaction of cyclopentadiene with a chiral dienophile in supercritical carbon dioxide (scCO2) proceeded rapidly to give the adduct with a higher diastereoselectivity than that in dichloromethane; optimization of the CO2 density increased the de value up to 77%.

ChemInform Abstract: The Use of 1‐Amino‐2‐phenyl‐1‐cyclohexanecarboxylic Acids as Chiral Auxiliaries in Asymmetric Diels‐Alder Reactions.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

The use of 1-amino-2-phenyl-1-cyclohexanecarboxylic acids as chiral auxiliaries in asymmetric Diels-Alder reactions

This report describes the behavior of four 1-amino-2-phenyl-1-cyclohexanecarboxylic acids, obtained in enantiomerically pure form starting from asymmetric Diels-Alder reactions between 1,3-butadiene and chiral (E)-2-cyanocinnamates, as chiral auxiliaries in the asymmetric Diels-Alder reactions of cyclopentadiene with chiral methyl N-acryloyl-1-amino-2-phenyl-1-cyclohexane-carboxylates. A model based on the formation of an intramolecular hydrogen bond accounts for the stereochemical outcome in the catalyzed reactions.

Synthesis of polymer-supported chiral N-sulfonylamino acids and their use in asymmetric diels-alder reaction of cyclopentadiene with methacrolein

Crosslinked polymer-supported chiral N -sulfonylamino acids have been synthesized by two methods; namely the chemical modification method and the copolymerization method. In the chemical modification method, the chlorosulfonyl group was introduced into styrenedivinylbenzene copolymers 1 by sulfonation with chlorosulfonic acid followed by chlorination with thionyl chloride. The degree of functionalization could be well controlled by the feed ratio of chlorosulfonic acid to aromatic rings of the polymer. Treatment of l -valine with the polymer having the chlorosulfonyl group 4 gave polymer-supported N -sulfonylated l -valine 5 . An alternative approach to the synthesis of chiral polymers involves the copolymerization of monomers containing the desired chiral groups with styrene and divinylbenzene (DVB). Suspension copolymerization of chiral monomers 6 , styrene, and DVB afforded the chiral polymers 7 in good yield. The N -sulfonylamino acid group in the polymer reacted with borane or monobromoborane to form chiral oxazaborolidinone 8 , which catalyzed the Diels-Alder reaction of cyclopentadiene with methacrolein, leading to optically active cycloadduct having enantiomeric purity of 65% ee. Graphic

Asymmetric Diels-Alder reaction of cyclopentadiene with methacrolein using polymer-supported chiral catalysts

Polymer-supported chiral Lewis acids were prepared from bromoboranes and crosslinked polymers having chiral amino alcohol or diol moieties. These polymers were used as chiral catalysts for Diels-Alder reactions of cyclopentadiene with methacrolein to give optically active cycloadduct in high chemical yield with high exo selectivity. Optical yield up to 54% ee was obtained by the use of polymeric chiral catalyst derived from ( S)-proline. The potential of this type of approach in asymmetric synthesis is discussed.

Asymmetric diels-alder reactions catalyzed by chiral oxazaborolidines. Effect of the position of an electron-donor functionality in the α-side chain substituent on the enantioselectivity

Abstract Asymmetric Diels-Alder reactions of cyclopentadiene with methacrolein and 2-bromoacrolein catalyzed by chiral oxazaborolidines 1 derived from N-tosyl-L-α-amino acids afforded cycloadducts in quantitative yield. Variation in the position of an electron donor atom in the α-side chain substituent shows that enantioselectivity is controlled by the presence of electron donor atoms in position 2 and 4.

Clay-catalysed asymmetric Diels-Alder reaction of cyclopentadiene with chiral acrylates

Clay-catalysed Diels-Alder reactions of cyclopentadiene with several chiral acrylates are studied. The results obtained show that these solids are not efficient catalysts when chiral auxiliaries of large size are used. Clay-catalysed reactions between cyclopentadiene and (R)-O-acryloylpantolactone are compared with non-catalysed and TiCl 4 and EtAlCl 2-catalysed reactions. With regard to diastereofacial selectivity, the clays studied behave like homogeneous aluminium catalysts. Clay-catalysed reactions of (R)-O-acryloylpantolactone lead to the (1S,2S,4S)-cycloadduct with good chemical yield, high % d.e. and excellent endo/exo selectivity. Given that (−)-menthyl acrylate leads to the (1R,2R,4R)-cycloadduct with about the same diastereofacial selectivity, (−)-menthol and (R)-pantolactone behave as complementary chiral auxiliaries.

AlPO 4-Catalysed asymmetric Diels-Alder reactions of cyclopentadiene with chiral acrylates

Reactions of cyclopentadiene with several chiral acrylates are studied and compared with the same reactions catalysed by Zn(II)-exchanged K10 montmorillonite. In general, amorphous AlPO 4 is a more efficient catalyst than the clay. In particular, the reaction of cyclopentadiene with (−)-8-phenylmenthyl acrylate leads to 74% diastereomeric excess (d.e.) in methylene chloride at low temperatures. This result constitutes the highest asymmetric induction described to date for a solid-catalysed asymmetric Diels-Alder reaction. When the reactions are carried out in the absence of a solvent a noticeable decrease in selectivity is observed, probably due to an extensive competition of the non-catalysed reaction.

Synthesis of Nucleosides and Related Compounds. XXVI. The Difference in Efects between High Pressure and LiClO4 for the Diels-Alder Reaction of Cyclopentadiene with Methylenemalonates or O-Acetylisonitrosomalonates.

Diels-Alder reactions of cyclopentadiene with methylenemalonates or O-acetylisonitrosomalonates in the presence of LiClO4 as the catalyst were examined and the results were compared with those obtained under high pressure without the catalyst. Diels-Alder reaction of cyclopentadiene with dimethyl acetoxymethylenemalonate (1) in the presence of LiClO4 afforded the [4+2] adduct (2) as a mixture of endo- and exo-isomers, whose ratio was 2.0, irrespective of the solvent or the concentration of LiClO4. Asymmetric Diels-Alder reaction of cyclopentadiene with di-l-methyl acetoxymethylenemalonate (3) was accelerated remarkably by LiClO4. The configurations of both endo and exo adducts corresponded to the natural form (D-form). These results suggested strongly that LiClO4 would behave as a bidentate Lewis acid catalyst just like titanium tetrachloride. the hetero Diels-Alder reaction of cyclopentadiene with O-acetylisonitrosomalonate in LiClO4-ether produced the adduct (5) in a higher yield than the reaction performed under high pressure.

Clay-catalysed asymmetric diels-alder reaction of cyclopentadiene with (−)-menthyl acrylate

Zn(II)-exchanged K10 montmorillonite is shown to be an efficient catalyst for the reaction between cyclopentadiene and (−)-menthyl acrylate, leading to the 1R,2R-cycloadduct with good chemical yield, high % d.e. and excellent endo/exo selectivity.

ChemInform Abstract: Asymmetric Diels‐Alder Reaction Using (S)‐Pyroglutamic Acid Derivatives as Chiral Dienophiles.

AbstractCondensation of the sodium salt of (S)‐5‐(methoxymethoxymethyl)‐2‐pyrrolidinone (I) with acryloyl chloride (IIa) and E‐crotonyl chloride (IIb) produces the corresponding N‐acyl derivatives (III).

Asymmetric Diels-Alder reaction using (S)-pyroglutamic acid derivatives as chiral dienophiles.

Asymmetric Diels-Alder reaction of cyclopentadiene with chiral dienophiles (3) derived from (S)-pyroglutamic acid derivatives was performed in the presence of a Lewis acid such as diethylaluminum chloride in toluene to afford the cycloadducts with high diastereoselectivity.