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.

Organocatalyzed Asymmetric Allylic Alkylation Enables Synthesis of Chiral γ-Lactones Bearing Vicinal Tertiary and Quaternary Stereocenters

The synthesis of enantioenriched α-aryl-α'-allyl-γ-butyrolactones bearing vicinal tertiary and quaternary stereocenters through organocatalyzed asymmetric allylic alkylation is reported. The process demonstrated that weakly stabilized enolates derived from α-aryl-γ-butyrolactones can undergo regio-, diastereo-, and enantioselective allylation using the proper activation of Morita-Baylis-Hillman (MBH) carbonates.

Organocatalytic enantioselective allylic alkylation of α-aryl γ-lactones: an approach to densely functionalized quaternary stereocentres

The asymmetric allylic alkylation (AAA) of α-aryl γ-lactones involving the activation of Morita-Baylis-Hillman (MBH) carbonates by an original chiral Lewis base is reported. A wide range of γ-lactones bearing a quaternary stereocentre was thus obtained in both high yields and high enantiomeric ratios. The direct alkylation by MBH alcohol using in situ activation has been also established. Additionally synthetically useful functional transformations of groups surrounding the quaternary stereocentre have been performed.

Highly enantioselective addition of sulfur-containing heterocycles to isatin-derived ketimines

In this study, we report a highly stereoselective addition of sulfur-containing heterocyclic compounds to isatin-derived ketimines efficiently catalyzed by cinchonidine-derived bifunctional tertiary aminothiourea (1 mol%).

Chemoselective SN2' Allylations of Detrifluoroacetylatively In Situ Generated 3-Fluoroindolin-2-one-Derived Tertiary Enolates with Morita-Baylis-Hillman Carbonates

The first example of the S_N2' reaction type of the detrifluoroacetylatively in situ generated tertiary fluoro-enolates in the uncatalyzed reactions with Morita-Baylis-Hillman derivatives has been described. The S_N2' substitution takes place in a highly chemoselective manner as no corresponding S_N2 products were observed in the reaction mixtures. Due to the excellent stereochemical outcome, the reactions seem to have an apparent synthetic value for the preparation of structurally new fluorinated oxindoles.

Diastereo- and enantioselective phase-transfer alkylation of 3-substituted oxindoles with racemic secondary alkyl halides

A catalytic asymmetric alkylation of fully substituted enolates with racemic, non-activated secondary alkyl halides is described.

Enantioselective Organocatalyzed Transformations of β-Ketoesters

The β-ketoester structural motif continues to intrigue chemists with its electrophilic and nucleophilic sites. Proven to be a valuable tool within organic synthesis, natural product, and medicinal chemistry, reports on chiral β-ketoester molecular skeletons display a steady increase. With the reignition of organocatalysis in the past decade, asymmetric methods available for the synthesis of this structural unit has significantly expanded, making it one of the most exploited substrates for organocatalytic transformations. This review provides comprehensive information on the plethora of organocatalysts used in stereoselective organocatalyzed construction of β-ketoester-containing compounds.

Regioselective addition–elimination of Morita–Baylis–Hillman adducts with 2-naphthol or phenol catalyzed by functionalized ionic liquids: a direct strategy to construct functional alkenes

A highly regioselective addition–elimination of Morita–Baylis–Hillman adducts promoted by base ionic liquids (0.5 mol%) was reported to afford a variety of functional alkenes in excellent yields (up to 99%). This protocol provides a new method to access functional alkenes directly. Recycled base ionic liquids could be reused at least five times and the isolated yield of the product was almost consistent after five runs.