exo-selective asymmetric Diels-Alder reaction catalyzed by diamine salts as organocatalysts

[reaction: see text] A novel binaphthyl-based diamine (R)-2 was designed and synthesized. A protonic acid-(R)-2 salt catalyst has the advantage of exhibiting unprecedented high exo selectivity in the asymmetric Diels-Alder reaction of alpha,beta-unsaturated aldehydes. For instance, the reaction between cinnamaldehyde and cyclopentadiene in the presence of 12 mol % of binaphthyl-based diamine (R)-2 and 10 mol % of p-TsOH.H(2)O in alpha,alpha,alpha-trifluorotoluene at -20 degrees C gave the corresponding exo cycloadduct with 92% ee as a major diastereomer (exo/endo = 13/1).     

Converting exo-selective Diels-Alder reaction to endo-selective in chloroloaluminate ionic liquids

The endo:exo ratio of 0.35:1 for the reaction of cyclopentadiene with methyl methacrylate observed in organic solvents can be converted to 3:1 in chloroaluminate ionic liquids with their effective reuse in Diels-Alder reactions.     

Diarylprolinol silyl ether as catalyst of an exo-selective, enantioselective Diels-Alder reaction

In combined use with CF3CO2H, 2-[bis(3,5-bis-trifluoromethylphenyl) triethylsiloxymethyl]pyrrolidine was found to be an effective organocatalyst of an exo-selective, enantioselective Diels-Alder reaction of alpha,beta-unsaturated aldehydes.     

Synthesis of precursors of the agalacto (exo) fragment of the quartromicins via an auxiliary-controlled exo-selective Diels-Alder reaction

[reaction: see text] A direct synthesis of the alpha-hydroxyaldehyde exo-5, a precursor of the exo-spirotetronate subunit of the quartromicins, was achieved through an exo-selective Lewis acid-catalyzed Diels-Alder reaction of dienophile 12a and diene 1.     

Aqueous Ti(IV)-catalyzed Diels-Alder reaction

The aqueous Diels-Alder reaction of 1,3-cyclohexadiene with 1,4-benzoquinone was compared and contrasted to the same reaction catalyzed with Flextyl P, a novel Ti(IV) performance catalyst. The catalyst improved conversion by 22% versus the uncatalyzed reaction and represents a rare example of a Ti(IV) catalyzed Diels-Alder reaction in water.     

Cobalt(II)-catalyzed intermolecular Diels-Alder reaction of piperine

[reaction: see text] An intermolecular cobalt-phosphine-catalyzed Diels-Alder reaction of piperine is described. The dimerization of piperine in the presence of cobalt-phosphine complexes gave much better yields than that in the presence of only cobalt, which, combined with the result under the purely thermal conditions, indicates that addition of phosphine ligands changes the inhibition of cobalt to the reaction into promotion. For elucidation of the distinction, different cobalt-catalyzed mechanisms were proposed for the Diels-Alder dimerization of piperine.     

Diels-Alder reaction of fulvenes with N-(3,5-dichlorophenyl)-maleimide

Summary N-(3,5-Dichlorophenyl)-maleimide reacts smoothly with a variety of substituted fulvenes (1) to give onlyendo adducts (3) independent of the nature of fulvene substituent,Lewis acid catalyst, and reaction solvent and temperature. The structure of theDiels-Alder adduct3f was determined by X-ray crystallography. Semi-empirical quantum methods (AM1) were used to rationalize theendo stereoselectivity.Dedicated to Professor Fritz Sauter on the occasion of his 65^th birthday     

Nitrosonium (NO) initiated and cation radical-mediated imino Diels-Alder reaction

An efficient aza-Diels-Alder reaction of N-arylimines with N-vinylpyrrolidinone was achieved using nitrosonium tetrafluoroborate as a cation radical initiator, giving cis-4-(2-oxopyrrolidin-1-yl)tetrahydroquinolines in various yields.     

Per(poly)fluoroalkanesulfinamides assisted diastereoselective three-component inverse-electron-demand aza Diels-Alder reaction

A highly diastereoselective three-component inverse-electron-demand aza Diels-Alder reaction assisted by per(poly)fluoro-alkanesulfinamides is presented, providing a broad spectrum of highly functionalized piperidine derivatives with excellent endo/exo and facial diastereoselectivities. The electron-withdrawing perfluoroalkyl groups are crucial for the success of this reaction under mild conditions and facilitate monitoring the process and stereoselectivities of the reaction. The synthetic potential of these cycloadducts is also highlighted.     

Catalytic enantioselective Diels-Alder reaction via a chiral indium(III) complex

[reaction: see text] A chiral indium complex has been developed to effect high enantioselectivities in catalyzing enantioselective Diels-Alder reaction. The cycloaddition of a variety of cyclic and open-chained dienes to 2-methacrolein and 2-bromoacrolein resulted in good yields and excellent enantioselectivities (up to 98% ee).     

Novel Diels-Alder reaction of 4-nitro-1(2H)-isoquinolones

A novel Diels-Alder (DA) reaction with 4-nitro-1(2H)-isoquinolones acting as the dienophile afforded 5(6H)-phenanthridone derivatives. The DA reaction of 4-nitro-1(2H)-isoquinolone with 1-methoxy-1,3-butadiene gave biologically active 5(6H)-phenanthridone possessing in a high yield. Regioselectivity of 4-nitro-1(2H)-isoquinolones with 1-methoxy-3-silyloxy-1,3-butadiene was calculated using molecular orbital (MO) calculations.     

Inclusion property and Diels-Alder reaction of bis (diphenylphosphine oxide) butadiyne

The host molecule, bis (diphenylphosphine oxide) butadiyne (2), includes a variety of guests to form five complexes (2a-2e). In addition, the Diels-Alder reaction between 2 and anthracene gives 9, 9', 10, 10'-tetrahedron-9, 9', 10, 10'-bi-ethenoantracene-11, 11'-bis ( diphenylphosphine oxide) (3) which is a potential di-π-methane reactant and can undergo photorearrangement.     

Consecutive Rh(I)-catalyzed Alder-ene/Diels-Alder/Diels-Alder reaction sequence affording rapid entry to polycyclic compounds

Conversion of acyclic allenynes to polycyclic compounds using consecutive transition metal catalyzed carbon-carbon bond forming reactions in a single chemical operation is described. Reaction of an allenyne with a Rh(I) catalyst affords a cross-conjugated triene via a formal Alder-ene reaction. The triene then participates in a Rh(I)-catalyzed intramolecular [4+2] cycloaddition reaction to generate a new conjugated diene. An external dienophile is added to this diene which then undergoes a second [4+2] cycloaddition reaction to afford a complex polycyclic ring system. This reaction sequence demonstrates the synthetic potential of allenynes and cross conjugated trienes and highlights the rapid increases in molecular complexity that are possible by one-pot sequential transition metal catalyzed carbon-carbon bond forming reactions.     

A comparison between ethylene dimerization and Diels-Alder reaction

The reaction pathways for the two reactions 2C₂H₄C₄H₈ and C₂H₄+C₄H₆ C₆H₁₀ were investigated. The transition state geometries and activation energies were determined with the SINDO method and compared. Both reactions were found concerted with different significance of diradical character at the transition state. Whereas the ethylene dimerization showed that a diradical will be encountered along the reaction pathway, we did not find one in the Diels-Alder reaction.     

2,3-二溴甲基喹喔啉与C60的Diels-Alder反应

Ｃ60 是富勒烯家族的一员[1] 。Ｃ60 分子的发现是Ｈ .Ｗ .Ｋｒｏｔｏ和Ｒ .Ｅ .Ｓｍａｌｌｅｙ等人于 1 985年 ,在氦气流中以激光蒸发石墨 ,从而获得以Ｃ60 为主的质谱图的 ,并在实验室制得了Ｃ60 分子[2 ] 。 1 990年德国科学家Ｋｒａｔｓｃｈｍｅｒ,Ｗ和美国科学家Ｈｕｆｆｍａｎ ,Ｄ .Ｒ .等用电弧法克量级制备Ｃ60 获得成功[3] 。从此 ,世界范围内掀起了一股Ｃ60 的研究热 ,对Ｃ60 进行各种化学修饰更是化学家的热门课题 ,经化学修饰的Ｃ60 衍生物具有潜在的应用前景。近几年 ,Ｃ60 化学反应的研究十分活跃 ,氧化反应、还原反应、聚合…     

Copper(II)-bis(oxazoline) catalyzed asymmetric Diels-Alder reaction with alpha'-arylsulfonyl enones as dienophiles

Alpha'-arylsulfonyl enones are efficient bidentate dienophiles for the Cu(II)-bis(oxazoline) catalyzed enantioselective Diels-Alder reaction with a number of dienes, affording the corresponding products with good to high enantiomeric excesses. The resulting products can be alkylated and the sulfone removed, so alpha'-arylsulfonyl enones can be regarded as surrogates of simple monodentate enones, which are poor dienophiles with this catalytic system.     

Highly stereoselective hydroxy-directed Diels-Alder reaction

The successful stereocontrol of the Diels-Alder reaction of semicyclic dienes possessing a secondary and tertiary allylic magnesium alkoxide alcohol functionality and activated dienophiles such as methyl acrylate, methacrolein, acrolein, and N-phenylmaleimide is described.     

Intramolecular Diels-Alder reaction of selenoaldehydes

Intramolecular Dieis-Alder reaction of selenoaldehydes which were generated from bis(trimethylsilyl) selenide and dienals gave the corresponding bicyclic adducts.