Organocatalytic Allylic Alkylation Research Articles

Chiral Phosphine Catalyzed Allylic Alkylation of Benzylidene Succinimides with Morita–Baylis–Hillman Carbonates

Owing to their unique chemical properties, α-alkylidene succinimides generally act as versatile synthons in organic synthesis. Compared with well-established annulations, nucleophilic alkylations of α-alkylidene succinimides are very limited. Accordingly, an organocatalytic allylic alkylation of α-benzylidene succinimides with Morita-Baylis-Hillman (MBH) carbonates was established. In the presence of a chiral phosphine catalyst, α-benzylidene succinimides reacted smoothly with MBH carbonates under mild conditions to furnish a series of optical active succinimides in high yields and enantioselectivities. Different from the reported results, the organocatalytic enantioselective construction of pyrrolidine-2,5-dione frameworks bearing contiguous chiral tertiary carbon centers was achieved via this synthetic strategy. Scaling up the reaction indicated that it is a practical strategy for the organocatalytic enantioselective alkylation of α-alkylidene succinimides. A possible reaction mechanism was also proposed.

Organocatalytic allylic alkylation of alkyne-substituted MBH carbonates: access to quaternary carbon-containing 1,4-enynes.

A DABCO-catalyzed allylic alkylation of tertiary propargylic alcohol-derived MBH carbonates with nitromethane was developed. A series of substituted 1,4-enynes with an all-carbon quaternary stereocenter were efficiently obtained in moderate to high yields. The synthetic utility of the product was demonstrated by facile synthesis of 1,4-enyne-embedded 2-pyrrolidinones.

Pentaenolate activation in the organocatalytic allylic alkylation of indene-2-carbaldehydes.

In this manuscript, the application of pentaenolate intermediates in the allylic alkylation of indene-2-carbaldehydes with Morita-Baylis-Hillman (MBH) carbonates is described. The reaction has been carried out in a highly enantio- and diastereoselective manner due to the use of a chiral tertiary amine as a nucleophilic catalyst. The developed reactivity constitutes the first application of organocatalytic pentaenolate activation in asymmetric synthesis, expanding the arsenal of catalytic methods.

Organocatalytic Allylic Alkylation of α-(Alkylideneamino)nitriles and Its Application in the Preparation of Multisubstituted 1-Pyrrolines.

A synthetic approach for the construction of functionalized diverse 1-pyrrolines incorporating β-quaternary carbon centers under mild reaction conditions has been reported, in which α-allyl α-(alkylideneamino)nitriles generated from a Lewis base-catalyzed allylic alkylation reaction engaged in a Lewis base-mediated tandem intramolecular cyclization to deliver the targeted molecules in a catalytically atom-economic fashion.

Insights into Organoamine-Catalyzed Asymmetric Synthesis of Axially Chiral Allenoates Using Morita-Baylis-Hillman Carbonates and Trisubstituted Allenoates: Mechanism and Origin of Stereoselectivity.

A computational study was performed to explore the possible mechanisms of β-isocinchonine-catalyzed asymmetric C(sp2)-H allylation of trisubstituted allenoates using Morita-Baylis-Hillman (MBH) carbonates for synthesis of axially chiral tetrasubstituted allenoates. The calculated results indicate that the most energetically favorable pathway includes (1) nucleophilic attack on MBH carbonate by β-isocinchonine, (2) BocO- dissociation, (3) stereoselective formation of the C-C bond, and (4) regeneration of the catalyst. By tracking the orbital overlap/interaction changes, the half shoulder-to-head orbital overlap mode can be smoothly switched to a head-to-head orbital overlap mode for the key C-C σ bond formation, which is also identified as the stereoselectivity-determining process. Further distortion/interaction, noncovalent interaction (NCI), and atom-in-molecule (AIM) analyses demonstrate that C-H···O and C-H···π interactions should be key for controlling the axial and central chirality. This work would be useful for rational design of organocatalytic allylic alkylation reactions for synthesis of axially chiral compounds in the future.

Highly diastereo- and enantioselective construction of phthalide-oxindole hybrids bearing vicinal quaternary chiral centers via an organocatalytic allylic alkylation

A diastereo- and enantioselective synthesis of phthalide-oxindole hybrids including congested adjacent quaternary chiral centers was demonstrated through a Lewis base catalyzed asymmetric allylic alkylation reaction of Morita–Baylis–Hillman carbonates of isatins and 3-cyanophthalides. The various hybrid molecules with two valuable pharmacophores-combined frameworks can be obtained in good to high diastereo- and enantioselectivities.

Regioselective synthesis of functionalized dihydroquinolines via organocatalytic allylic alkylation

The regioselective allylic alkylation of 1,2-dihydroquinolines and Morita-Baylis-Hillman(MBH) adducts has been developed. By surveying various reaction parameters, we summarize the effects of temperatures, relative reactant doses, catalysts, solvents and N-protected groups on the regioselectivity of this transformation. This method provides a facile protocol for the preparation of allylic α-substituted dihydroquinolines.

Synthesis of functionalized 1,2-dihydropyridines bearing quaternary carbon centers via an organocatalytic allylic alkylation

The first tertiary amine-catalyzed allylic alkylation of Reissert products of pyridine derivatives has been demonstrated. This protocol provided an efficient synthetic route for the construction of functionalized 2,2-disubstituted 1,2-dihydropyridines incorporating quaternary carbon centers with good to high regioselectivities and moderate enantioselectivities.

ChemInform Abstract: Enantioselective Desymmetrization of Prochiral 1,3‐Dinitropropanes via Organocatalytic Allylic Alkylation.

An enantioselective desymmetrization of prochiral 1,3-dinitropropanes has been developed which proceeds via enantiogroup differentiating organocatalytic allylic alkylation. Densely functionalized products with two vicinal stereocenters were obtained generally with good to excellent diastereoselectivity (up to >20 : 1 dr) and superb enantioselectivity (up to >99 : 1 er).

Enantioselective desymmetrization of prochiral 1,3-dinitropropanes via organocatalytic allylic alkylation

An enantioselective desymmetrization of prochiral 1,3-dinitropropanes has been developed which proceeds via enantiogroup differentiating organocatalytic allylic alkylation. Densely functionalized products with two vicinal stereocenters were obtained generally with good to excellent diastereoselectivity (up to >20 : 1 dr) and superb enantioselectivity (up to >99 : 1 er).

ChemInform Abstract: Asymmetric Organocatalytic Allylic Alkylation of Reissert Compounds: A Facile Access to Chiral 1,1‐Disubstituted 1,2‐Dihydroisoquinolines.

The first asymmetric organocatalytic allylic alkylation of 1,2-dihydro-Reissert compounds and Morita-Baylis-Hillman (MBH) carbonates has been developed, which provided a novel protocol to construct enantioenriched functionalized 1,2-dihydroisoquinolines bearing vicinal quaternary and tertiary chiral centers at C-1 position (up to 94% ee, dr > 20 : 1).

Asymmetric organocatalytic allylic alkylation of Reissert compounds: a facile access to chiral 1,1-disubstituted 1,2-dihydroisoquinolines

The first asymmetric organocatalytic allylic alkylation of 1,2-dihydro-Reissert compounds and Morita-Baylis-Hillman (MBH) carbonates has been developed, which provided a novel protocol to construct enantioenriched functionalized 1,2-dihydroisoquinolines bearing vicinal quaternary and tertiary chiral centers at C-1 position (up to 94% ee, dr > 20 : 1).

Construction of Adjacent Quaternary and Tertiary Stereocenters via an Organocatalytic Allylic Alkylation of Morita—Baylis—Hillman Carbonates.

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Construction of Adjacent Quaternary and Tertiary Stereocenters via an Organocatalytic Allylic Alkylation of Morita–Baylis–Hillman Carbonates

AbstractRacemic Baylis–Hillman carbonates can be converted in densely functionalized products by reaction with cyano esters in the presence of a catalytic amount of a modified Cinchona alkaloid in high enantioselectivities and fair diastereoselectivities. A rational for the observed stereoselectivity is presented.

Regio‐ and Stereoselective Construction of γ‐Butenolides Through Phosphine‐Catalyzed Substitution of Morita—Baylis—Hillman Acetates: An Organocatalytic Allylic Alkylation.

Regio‐ and Stereoselective Construction of γ‐Butenolides Through Phosphine‐Catalyzed Substitution of Morita—Baylis—Hillman Acetates: An Organocatalytic Allylic Alkylation.

Regio‐ and Stereoselective Construction of γ‐Butenolides through Phosphine‐Catalyzed Substitution of Morita–Baylis–Hillman Acetates: An Organocatalytic Allylic Alkylation

Regio‐ and Stereoselective Construction of γ‐Butenolides through Phosphine‐Catalyzed Substitution of Morita–Baylis–Hillman Acetates: An Organocatalytic Allylic Alkylation

Regio‐ and Stereoselective Construction of γ‐Butenolides through Phosphine‐Catalyzed Substitution of Morita–Baylis–Hillman Acetates: An Organocatalytic Allylic Alkylation

Regio‐ and Stereoselective Construction of γ‐Butenolides through Phosphine‐Catalyzed Substitution of Morita–Baylis–Hillman Acetates: An Organocatalytic Allylic Alkylation