A Mild and Efficient Asymmetric Hetero-Diels-Alder Reaction of the Brassard Diene with Aldehydes

Total Synthesis of (R)-Argentilactone and (R)-Goniothalamin Using a Free-Radical Photoredox Approach to α,β-Unsaturated δ-Lactones

α,β-Unsaturated δ-lactones are structural motifs found in diverse pharmacologically active natural products. In fact, the unsaturated lactone is often responsible for the biological activity. Herein, we report a new approach for the syntheses of (R)-argentilactone and (R)-goniothalamin based on a photoredox intermolecular iodolactonization mediated by a photoredox process. This new approach, already employed in our research group, stands as a new methodology to achieve several natural products containing α,β-unsaturated δ-lactones.

Stereoselective three-component cascade synthesis of α-substituted 2,4-dienamides from gem-difluorochloro ethanes

Herein, we describe a new transition metal-free Claisen rearrangement for the synthesis of α-substituted 2,4-dienamides. The one-pot, stereoselective three-component cascade reaction between a series of propargyl alcohols, amines, and gem-difluorochloro ethane derivatives afforded various polysubstituted 2,4-dienamides in good yields. This synthetic method for 1,1-captodative dienes, α-substituted 2,4-dienamides, can be utilized for preparing pharmaceutical analogues containing an indolin-2-one or lactone moiety.

Catalytic asymmetric oxo-Diels-Alder reactions with chiral atropisomeric biphenyl diols

New chiral atropisomeric biphenyl diols 3, 4 and 6 containing additional peripheral chiral centers with different steric bulkiness and/or electronic properties were synthesized. The X-ray crystal structure of 3 shows the formation of a supramolecular structure whereas that of 6, containing additional CF₃ substituents, shows the formation of a monomeric structure. Diols 1–6 were found to be active organocatalysts in oxo-Diels–Alder reactions in which 2 recorded a 72% ee with trimethylacetaldehyde as a substrate.

Catalytic Asymmetric Inverse-Electron-Demand Hetero-Diels-Alder Reactions

In this review, the recent developments in catalytic asymmetric inverse-electron-demand hetero-Diels-Alder reaction, which is recognized as one of the most powerful routes to construct highly functionalized and enantioenriched six-membered heterocycles, are described. The article is organized on the basis of different kinds of electron-deficient heterodienes, including α,β-unsaturated ketones/aldehydes, o-benzoquinones, α,β-unsaturated imines, N-aryl imines, o-benzoqinone imides, and other aza-olefins.