Iron-catalyzed asymmetric inverse-electron-demand hetero-Diels-Alder reaction of dioxopyrrolidines with simple olefins.

The asymmetric catalytic inverse-electron-demand hetero-Diels-Alder reaction of dioxopyrrolidines with a variety of simple olefins has been accomplished, significantly expanding the applicability of this cyclization to both cyclic hetero-dienes and dienophiles. A new type of strong Lewis acid catalyst of ferric salt enables the LUMO activation of dioxopyrrolidines formation of cationic species, this method yields a range of bicyclic dihydropyran derivatives with exceptional outcomes, including high yields (up to 99%), diastereoselectivity (up to 99 : 1) and enantioselectivity (up to 99% ee) under mild conditions. This facile protocol was available for the late-stage modification of several bioactive molecules and transformation into macrocycle molecules as well.

Enantioselective Radical Addition to Ketones through Lewis Acid-Enabled Photoredox Catalysis.

Photocatalysis opens up a new window for carbonyl chemistry. Despite a multitude of photochemical reactions of carbonyl compounds, visible light-induced catalytic asymmetric transformations remain elusive and pose a formidable challenge. Accordingly, the development of simple, efficient, and economic catalytic systems is the ideal pursuit for chemists.

Nickel-catalyzed asymmetric photoenolization/Mannich reaction of (2-alkylphenyl) ketones.

A diastereo- and enantioselective photoenolization/Mannich (PEM) reaction of -alkyl aromatic ketones with benzosulfonimides was established by utilizing a chiral ,'-dioxide/Ni(OTf) complex as the Lewis acid catalyst. It afforded a series of benzosulfonamides and the corresponding ring-closure products, and a reversal of diastereoselectivity was observed through epimerization of the benzosulfonamide products under continuous irradiation. On the basis of the control experiments, the role of the additive LiNTf in achieving high stereoselectivity was elucidated.

Catalytic Asymmetric Three-component Hydroacyloxylation/ 1,4-Conjugate Addition of Ynamides.

A highly enantioselective three-component hydroacyloxylation/1,4-conjugate addition of ortho-hydroxybenzyl alcohols, ynamides and carboxylic acids was developed under mild reaction conditions in the presence of a chiral N,N'-dioxide/Sc(OTf) complex, which went through in situ generated ortho-quinone methides with α-acyloxyenamides, delivering a range of corresponding chiral α-acyloxyenamides derivatives containing gem(1,1)-diaryl skeletons in moderate to good yields with excellent ee values. The scale-up experiment and further derivation showed the practicality of this catalytic system. In addition, a possible catalytic cycle and transition state model was proposed to elucidate the origin of the stereoselectivity based on X-ray crystal structure of the α-acyloxyenamide intermediate and product.