Cycloaddition Of Vinylcyclopropanes Research Articles

ChemInform Abstract: Asymmetric [3 + 2] Cycloaddition of Vinylcyclopropanes and α,β‐Unsaturated Aldehydes by Synergistic Palladium and Organocatalysis

Abstractaffording highly substituted cyclopentanes with up to four stereocenters in high yields and selectivities

ChemInform Abstract: Asymmetric Preparation of Polysubstituted Cyclopentanes by Synergistic Pd(0)/Amine Catalyzed Formal [3 + 2] Cycloadditions of Vinyl Cyclopropanes with Enals.

We report herein a novel diastereo- and enantiocontrolled preparation of polysubstituted cyclopentanes by the formal [3+2] cycloadditions of vinyl cyclopropanes with enals. In constrast with previously developed strategies, our original approach is based on the synergistic merger of iminium/enamine organocatalysis with palladium(0) catalysis.

Asymmetric [3 + 2] Cycloaddition of Vinylcyclopropanes and α,β-Unsaturated Aldehydes by Synergistic Palladium and Organocatalysis.

The stereoselective [3 + 2] cycloaddition between vinylcyclopropanes and α,β-unsaturated aldehydes promoted by combined palladium and organocatalysis is disclosed. The unique synergistic catalytic system allows for the stereoselective formation of highly substituted cyclopentanes with up to four stereocenters in high yields and selectivities. Vinylcyclopropanes with two different geminal substituents facilitate the formation of cyclopentanes containing a quaternary stereocenter. Furthermore, the developed reaction performs well on gram scale, and a number of transformations are demonstrated.

Fe2(CO)9-mediated [5+1] cycloaddition of vinylcyclopropanes and CO for the synthesis of α, β-cyclohexenones

A Fe2(CO)9-mediated [5+1] cycloaddition of vinylcyclopropanes (VCPs) and CO to α, β-cyclohexenones has been developed. The reaction can tolerate aryl and aliphatic groups at the α-position of VCPs, while VCP substrates with vinyl or alkynyl substitutions are not suitable ones. In addition, this reaction can also be used to synthesize bicyclic rings if an aryl group is attached to the vinyl moiety of the substrate. Compared to the Fe(CO)5-mediated [5+1] reaction, the use of cheap and safe Fe2(CO)9 and abandoning the photo-irradiation conditions are the two major advantages of the present method.

Asymmetric preparation of polysubstituted cyclopentanes by synergistic Pd(0)/amine catalyzed formal [3+2] cycloadditions of vinyl cyclopropanes with enals.

We report herein a novel diastereo- and enantiocontrolled preparation of polysubstituted cyclopentanes by the formal [3+2] cycloadditions of vinyl cyclopropanes with enals. In constrast with previously developed strategies, our original approach is based on the synergistic merger of iminium/enamine organocatalysis with palladium(0) catalysis.

ChemInform Abstract: Transition Metal‐Catalyzed Cycloadditions of Cyclopropanes for the Synthesis of Carbocycles: C‐C Activation in Cyclopropanes

AbstractReview: 140 refs.

ChemInform Abstract: Highly Enantioselective [3 + 2] Cycloaddition of Vinylcyclopropane with Nitroalkenes Catalyzed by Palladium(0) with a Chiral Bis(tert‐Amine) Ligand.

AbstractThe title reaction affords spiropentyl indane‐1,3‐dione derivatives (III) in high yields with good diastereoselectivities and excellent enantioselectivities.

Iridium catalyzed carbocyclizations: efficient (5+2) cycloadditions of vinylcyclopropanes and alkynes.

Third-row transition metal catalysts remain a largely untapped resource in cycloaddition reactions for the formation of medium-sized rings. Herein, we report the first examples of iridium-catalyzed inter- and intramolecular vinylcyclopropane (VCP)-alkyne (5+2) cycloadditions. DFT modeling suggests that catalysis by iridium(I) proceeds through a mechanism similar to that previously reported for rhodium(I)-catalyzed VCP-alkyne cycloadditions, but a smaller free energy span for iridium enables substantially faster catalysis under favorable conditions. The system is characterized by up to quantitative yields and is amenable to an array of disubstituted alkynes and vinylcyclopropanes.

Transition metal-catalyzed cycloadditions of cyclopropanes for the synthesis of carbocycles: C-C activation in cyclopropanes.

Transition metal-catalyzed cycloadditions of cyclopropanes have been well developed over the past several decades, leading to numerous new types of cycloadditions which are complementary to the traditional cycloadditions for the synthesis of carbocycles. Cycloadditions of vinylcyclopropanes (VCPs) and methylenecyclopropanes (MCPs) constitute two main aspects of this field. VCPs can act either as five-carbon synthons or three-carbon synthons, depending on whether the vinyl substituent is acting as an additional two-carbon synthon or not. As five-carbon synthons, VCPs are involved in [5+1], [5+2], [5+2+1], and [5+1+2+1] cycloadditions. As three-carbon synthons, VCPs are mainly involved in [3+2] and [3+2+1] cycloadditions. MCPs mostly act as three-carbon synthons and can have [3+2] cycloadditions with different π systems. Other types of cycloadditions involving MCPs are also reviewed, such as [3+1], [3+2+2], and [4+3+2] cycloadditions. Cycloadditions of some other unusual cyclopropane derivatives are also introduced briefly. The cycloadditions of VCPs and MCPs have found applications in total synthesis and some representative molecules are tabulated as selected examples.

Diastereo- and Enantioselective Construction of Oxindole-Fused Spirotetrahydrofuran Scaffolds through Palladium-Catalyzed Asymmetric [3+2] Cycloaddition of Vinyl Cyclopropanes and Isatins

A novel asymmetric formal [3+2] cycloaddition of vinyl cyclopropanes and isatins in the presence of Pd2(dba)3 and the chiral imidazoline-phosphine ligand (aS,R,R)-L3 has been developed, affording the corresponding highly functionalized oxindole-fused spirotetrahydrofuran frameworks in good yields along with good diastereo- and high enantioselectivities under mild conditions.

Palladium-Catalyzed Asymmetric Formal [3+2] Cycloaddition of Vinyl Cyclopropanes and β,γ-Unsaturated α-Keto Esters: An Effective Route to Highly Functionalized Cyclopentanes

Palladium-catalyzed asymmetric formal [3+2] cycloaddition of vinyl cyclopropanes and β,γ-unsaturated α-keto esters proceeded smoothly in the presence of chiral imidazoline–phosphine ligands to give the corresponding highly functionalized cyclopentanes in good yields along with high diastereo- and enantioselectivities under mild conditions.

Ligand Effects on Rates and Regioselectivities of Rh(I)-Catalyzed (5 + 2) Cycloadditions: A Computational Study of Cyclooctadiene and Dinaphthocyclooctatetraene as Ligands

The first theoretical study on the effects of ligands on the mechanism, reactivities, and regioselectivities of Rh(I)-catalyzed (5 + 2) cycloadditions of vinylcyclopropanes (VCPs) and alkynes has been performed using density functional theory (DFT) calculations. Highly efficient and selective intermolecular (5 + 2) cycloadditions of VCPs and alkynes have been achieved recently using two novel rhodium catalysts, [Rh(dnCOT)](+)SbF(6)(-) and [Rh(COD)](+)SbF(6)(-), which provide superior reactivities and regioselectivities relative to that of the previously reported [Rh(CO)(2)Cl](2) catalyst. Computationally, the high reactivities of the dnCOT and COD ligands are attributed to the steric repulsions that destabilize the Rh-product complex, the catalyst resting state in the catalytic cycle. The regioselectivities of reactions with various alkynes and different Rh catalysts are investigated, and a predictive model is provided that describes substrate-substrate and ligand-substrate steric repulsions, electronic effects, and noncovalent π/π and C-H/π interactions. In the reactions with dnCOT or COD ligands, the first new C-C bond is formed proximal to the bulky substituent on the alkyne to avoid ligand-substrate steric repulsions. This regioselectivity is reversed either by employing the smaller [Rh(CO)(2)Cl](2) catalyst to diminish the ligand-substrate repulsions or by using aryl alkynes, for which the ligand-substrate interactions become stabilizing due to π/π and C-H/π dispersion interactions. Electron-withdrawing groups on the alkyne prefer to be proximal to the first new C-C bond to maximize metal-substrate back-bonding interactions. These steric, electronic, and dispersion effects can all be utilized in designing new ligands to provide regiochemical control over product formation with high selectivities. The computational studies reveal the potential of employing the dnCOT family of ligands to achieve unique regiochemical control due to the steric influences and dispersion interactions associated with the rigid aryl substituents on the ligand.

Rhodium Dinaphthocyclooctatetraene Complexes: Synthesis, Characterization and Catalytic Activity in [5+2] Cycloadditions

Rh COT in the act: a Ni(0)-catalyzed [2+2+2+2] cycloaddition provides a high-yielding, scalable synthesis of the ligand dinaphtho[a,e]cyclooctatetraene (dnCOT). dnCOT complexation with Rh(I) gives [Rh(dnCOT)(MeCN)(2)]SbF(6), an excellent catalyst for [5+2] cycloadditions of vinylcyclopropanes and π-systems with impressive functional group compatibility.

Rh(I)-Catalyzed [5 + 1] Cycloaddition of Vinylcyclopropanes and CO for the Synthesis of α,β- and β,γ-Cyclohexenones

A cationic Rh(I)-catalyzed [5 + 1] cycloaddition of vinylcyclopropanes and CO has been developed, affording either β,γ-cyclohexenones as major products or α,β-cyclohexenones exclusively, under different reaction conditions.

ChemInform Abstract: Palladium‐Catalyzed Diastereo‐ and Enantioselective Synthesis of Substituted Cyclopentanes Through a Dynamic Kinetic Asymmetric Formal [3 + 2]‐Cycloaddition of Vinyl Cyclopropanes and Alkylidene Azlactones.

AbstractVinyl cyclopropane (I) is used in asymmetric cycloadditions with a range of aryl, heterocyclic, alkenyl, and alkyl substituted azlactone alkylidenes.

Palladium-catalyzed diastereo- and enantioselective synthesis of substituted cyclopentanes through a dynamic kinetic asymmetric formal [3+2]-cycloaddition of vinyl cyclopropanes and alkylidene azlactones.

An enantioselective preparation of vinylcyclopentanes has been achieved through the title reaction (see scheme). A range of aryl, heterocyclic, alkenyl, and alkyl substituted azlactone alkylidenes have been utilized, giving the cyclopentane products in good yield, diastereomeric ratio, and enantioselectivity.

Palladium‐Catalyzed Diastereo‐ and Enantioselective Synthesis of Substituted Cyclopentanes through a Dynamic Kinetic Asymmetric Formal [3+2]‐Cycloaddition of Vinyl Cyclopropanes and Alkylidene Azlactones

Palladium‐Catalyzed Diastereo‐ and Enantioselective Synthesis of Substituted Cyclopentanes through a Dynamic Kinetic Asymmetric Formal [3+2]‐Cycloaddition of Vinyl Cyclopropanes and Alkylidene Azlactones

Highly Efficient, Facile, Room Temperature Intermolecular [5 + 2] Cycloadditions Catalyzed by Cationic Rhodium(I): One Step to Cycloheptenes and Their Libraries

A cationic rhodium(I) complex--[(C(10)H(8))Rh(cod)](+) SbF(6)(-)--catalyzes the remarkably efficient intermolecular [5 + 2] cycloaddition of vinylcyclopropanes (VCPs) and various alkynes, providing cycloheptene cycloadducts in excellent yields in minutes at room temperature. The efficacy and selectivity of this catalyst are also shown in a novel diversification strategy, affording a cycloadduct library in one step from nine commercially available components.

A Metal-Catalyzed Intermolecular [5+2] Cycloaddition/Nazarov Cyclization Sequence and Cascade

The bicyclo[5.3.0]decane skeleton is one of the most commonly encountered bicyclic subunits in nature and the core scaffold of a wide range of targets of structural, biological, and therapeutic importance. Prompted by the interest in such structures, we report the first studies of metal-catalyzed [5+2] cycloadditions of vinylcyclopropanes (VCPs) and enynones. The resultant efficiently formed dienone cycloadducts serve as substrates for subsequent Nazarov cyclizations and as intermediates for single-operation [5+2]/Nazarov serial reactions and catalytic cascades. In many cases the one-flask process can be carried out in shorter reaction times and with comparable or superior yields to the two-flask procedure. Significantly, a single catalyst can be used to mediate both transformations. These [5+2]/Nazarov reaction sequences and cascades collectively provide strategically novel and facile access to the bicyclo[5.3.0]decane skeleton from simple and readily available components.

ChemInform Abstract: Diastereoselective Synthesis of Tetrahydrofurans via Palladium(0)‐Catalyzed [3 + 2] Cycloaddition of Vinylcyclopropanes and Aldehydes.

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