Asymmetric Diels Research Articles

Synthesis of Optically Pure Spiro[cyclohexane-oxindoline] Derivatives via Catalytic Asymmetric Diels-Alder Reaction of Brassard-Type Diene with Methyleneindolines.

A highly efficient N,N'-dioxide-Zn(II) complex catalytic system for the asymmetric Diels-Alder reaction of Brassard-type diene with methyleneindolines was developed. The optically pure spiro[cyclohex[3]ene-1,3'-indoline]-1'-carboxylate-2, 2'-dione derivatives containing three stereocenters were obtained in moderate yields with 98% to >99% ee in a stereospecific manner.

Chiral Holmium Complex-Catalyzed Synthesis of Hydrocarbazole from Siloxyvinylindole and Its Application to the Enantioselective Total Synthesis of (-)-Minovincine.

The catalytic and enantioselective total synthesis of (-)-minovincine has been accomplished. The key highly substituted hydrocarbazole derivative was obtained by an asymmetric Diels-Alder reaction of siloxyvinylindole catalyzed by 0.5 mol % of a chiral holmium complex. The Diels-Alder adduct was converted to a tetracyclic intermediate in a one-pot procedure. No waste stereoisomers were produced throughout the entire total synthesis.

ChemInform Abstract: Catalytic Asymmetric Diels—Alder Reaction of Quinone Imine Ketals: A Site‐Divergent Approach.

AbstractThe site selectivity in these asymmetric quinone Diels—Alder reactions strongly depends on the structure of the axially chiral dicarboxylic acid catalyst.

Zinc-Catalyzed Asymmetric Diels–Alder Reaction

Zinc-Catalyzed Asymmetric Diels–Alder Reaction

ChemInform Abstract: Broensted Acid Catalyzed Asymmetric Diels—Alder Reactions: Stereoselective Construction of Spiro[tetrahydrocarbazole‐3,3′‐oxindole] Framework.

AbstractUnless otherwise mentioned the products are obtained with <95:5 d.r.

Development of DNA Metalloenzymes Using a Rational Design Approach and Application in the Asymmetric Diels–Alder Reaction

We report here DNA metalloenzymes that catalyzed the asymmetric Diels–Alder reactions with high conversion, excellent endo/exo selectivities, and enantioselectivities up to −97% ee. Their catalytic-pocket architectures were organized using a rational design strategy based on the Cu(II) ion, the composition of nucleobases, and the incorporation of flexible linkers. Without using the mirror image of B-DNA, DNA metalloenzymes afforded the opposite enantiomer of the Diels–Alder product compared with those obtained using a supramolecular Cu(II)–dmbpy/st–DNA catalyst system. Furthermore, we devised DNA metalloenzymes without the incorporation of an artificial binding ligand and successfully performed Diels–Alder carbon–carbon bond-forming reactions. This study provides a new perspective on the catalytic repertoire of nucleic acids in the realm of protein-dominated metalloenzymes.

ChemInform Abstract: Efficient Organocatalyst Supported on a Simple Ionic Liquid as a Recoverable System for the Asymmetric Diels—Alder Reaction in the Presence of Water.

This work was supported by the Ministerio de Ciencia e Innovacion (MICINN) and FEDER Program (Madrid, Spain, project CTQ2013-44367-C2-1-P) and the Gobierno de Aragon (Zaragoza, Spain. D.R.-L. thanks the Spanish Ministry of Education (MEC) for a pre-doctoral grant (FPU program). We thank the Italian Ministry of University and Scientific Research (MIUR) for a doctoral grant and the University of Calabria for financial support.

ChemInform Abstract: Organocatalytic Diels—Alder Reaction of 2‐Vinylindoles with Methyleneindolinones: An Efficient Approach to Functionalized Carbazolespirooxindoles.

AbstractAn unprecedented asymmetric Diels—Alder reaction is described.

Synthesis and Properties of a Novel Pyridineoxazoline Containing Optically Active Helical Polymer as a Catalyst Ligand for Asymmetric Diels-Alder Reaction.

A novel pyridineoxazoline (PyOx) containing helical polymer, poly{(-)-(S)-4-tert-butyl-2-[5-(4-tert-butylphenyl)-3-vinylpyridin-2-yl]-oxazoline} (PA), was designed and synthesized to approach the effect of chain conformation on the catalytic property. Its complex with Cu(OTf)(2) , i.e., Cu(II)-PA, was employed to catalyze the homogeneous Diels-Alder (D-A) reaction of alkenoyl pyridine N-oxides with cyclopentadiene in tetrahydrofuran. Compared with the previously reported copper complex, Cu(II)-P1 (RSC Advances, 2015, 5, 2882), which was derived from a nonhelical poly[(-)-(S)-4-tert-butyl-2-(3-vinylpyridin-2-yl)-oxazoline], Cu(II)-PA exhibited a remarkably enhanced enantioselectivity and reaction rate. However, its enantioselectivity was lower than the Cu(II) complex of (-)-(S)-4-tert-butyl-2-[5-(4-tert-butylphenyl)-3-vinylpyridin-2-yl]-oxazoline (Cu(II)-A), a low molar mass model compound.

Catalytic Asymmetric Diels–Alder Reaction of Quinone Imine Ketals

Catalytic Asymmetric Diels–Alder Reaction of Quinone Imine Ketals

Organocatalytic Diels–Alder Reaction of 2‐Vinylindoles with Methyleneindolinones: An Efficient Approach to Functionalized Carbazolespirooxindoles

AbstractAn unprecedented asymmetric Diels–Alder reaction of 2‐vinylindoles with methyleneindolinones has been disclosed. Under bifunctional organocatalysis by cinchona‐derived squaramide catalyst, a series of diversely functionalized carbazolespirooxindole derivatives bearing three contiguous stereocenters are rapidly constructed under mild conditions (48–90% yields, up to >20:1 dr and 99% ee).magnified image

Catalytic Asymmetric Diels–Alder Reaction of Quinone Imine Ketals: A Site‐Divergent Approach

AbstractThe catalytic asymmetric Diels–Alder reaction of quinone imine ketals with diene carbamates catalyzed by axially chiral dicarboxylic acids is reported herein. A variety of primary and secondary alkyl‐substituted quinone derivatives which have not been applied in previous asymmetric quinone Diels–Alder reactions could be employed using this method. More importantly, we succeeded in developing a strategy to divert the reaction site in unsymmetrical 3‐alkyl quinone imine ketals from the inherently favored unsubstituted CC bond to the disfavored alkyl‐substituted CC bond.

Catalytic asymmetric diels-alder reaction of quinone imine ketals: a site-divergent approach.

The catalytic asymmetric Diels-Alder reaction of quinone imine ketals with diene carbamates catalyzed by axially chiral dicarboxylic acids is reported herein. A variety of primary and secondary alkyl-substituted quinone derivatives which have not been applied in previous asymmetric quinone Diels-Alder reactions could be employed using this method. More importantly, we succeeded in developing a strategy to divert the reaction site in unsymmetrical 3-alkyl quinone imine ketals from the inherently favored unsubstituted C=C bond to the disfavored alkyl-substituted C=C bond.

Lewis acid template-catalyzed asymmetric diels-alder reaction.

An asymmetric Diels-Alder reaction of 2,4-dienols and methyl acrylate utilizing a chiral Zn(II)/Mg(II) bimetallic template with low catalyst loading was successfully achieved. The bimetallic Lewis acid template derived from (R)-5,5',6,6',7,7',8,8'-octahydro-1,1'-bi-2-naphthol catalyzed the Diels-Alder reaction in the presence of molecular sieves 4 Å to afford various functionalized bicyclic γ-lactones with high enantiomeric purities.

Efficient Organocatalyst Supported on a Simple Ionic Liquid as a Recoverable System for the Asymmetric Diels–Alder Reaction in the Presence of Water

AbstractThe synthesis, characterization, and evaluation of a new highly efficient organocatalyst, namely, (5S)‐2,2,3‐trimethyl‐5‐thiobenzylmethyl‐4‐imidazolidinone hydrochloride, has been achieved. The catalyst possesses important structural features that should increase the catalytic efficiency and solubility in polar media. The application of the ionic‐liquid‐supported imidazolidinone catalyst in enantioselective Diels–Alder reactions was investigated. The Diels–Alder reactions of several dienes and dienophiles proceeded efficiently in the presence of the catalyst to provide the desired products in moderate to good yields and from good to excellent enantioselectivities. The conformation study confirms that in the transition state the Re face is shielded completely by the phenyl ring and an approach on the less hindered Si face is preferred. Particularly remarkable is the fact that the entire ionic liquid/HCl 0.01 M/catalyst system can be recovered and reused in up to six runs without an appreciable loss of catalytic activity.

Synthesis of MacMillan catalyst modified with ionic liquid as a recoverable catalyst for asymmetric Diels–Alder reaction

MacMillan catalyst was modified with imidazolium ionic liquid by ester linkage and acts as recoverable and reusable catalyst for asymmetric Diels–Alder reactions.

Synthesis and properties of a novel Cu(ii)–pyridineoxazoline containing polymeric catalyst for asymmetric Diels–Alder reaction

Soluble and recyclable Cu(ii)–pyridineoxazoline containing polymeric catalyst shows faster reaction rate and higher enantio-selectivity than its low molecular mass counterpart in D–A reaction of 2-alkenoyl pyridine N-oxide and cyclopentadiene.

New insights into the asymmetric Diels–Alder reaction: the endo- and S-selective retro-Diels–Alder reaction

The endo- and S-selective retro-Diels–Alder reactions have been proposed and verified in an imidazolethione-catalyzed asymmetric Diels–Alder reaction.

Trienamine catalysis for asymmetric Diels-Alder reactions of 2,4-dienones: a theoretical investigation.

The mechanism and origin of the selectivity of asymmetric Diels-Alder reactions of 2,4-dienones (R1) by trienamine catalysis is investigated at the M06-2X/6-311++G**(SMD, toluene)//B3LYP/6-311G** level. The acidic additive (salicylic acid or trifluoroacetic acid) promotes the isomerization of the ketoiminium ion into the key reactive cis-trienamine catalytic species with a preferred conformation by constructing a suitable hydrogen-bond bridge for a H shift. One-step cycloaddition was adopted for N-phenylmaleimide (R2), while a stepwise process was used for benzylidenecyanoacetate (R3) dienophile. The -CN and -CO2Et substituents in R3 may play an important role in forming a zwitterionic intermediate by participating in charge transfer by trienamine catalysis. The combination of a hydrogen bond from the protonated N atom of the tertiary amine and steric repulsion from the α-aryl group of trienamine makes the dienophile substrates approach the trienamine from one preferred face. The orbital factors define the most favored alignment of the trienamine and dienophile to realize the endo-selectivity of the product.

ChemInform Abstract: Asymmetric Dearomatic Diels—Alder Reactions of Diverse Heteroarenes via π‐System Activation.

AbstractThe reactions generally proceed with excellent diastereoselectivity.