Quantitative, Regiospecific, and Stereoselective Radical Ring-Opening Polymerization of Monosaccharide Cyclic Ketene Acetals.

Cyclic ketene acetals (CKAs) are among the most well-studied monomers for radical ring-opening polymerization (rROP). However, ring-retaining side reactions and low reactivities in homopolymerization and copolymerization remain significant challenges for the existing CKAs. Here, we report that a class of monosaccharide CKAs can be facilely prepared from a short and scalable synthetic route and can undergo quantitative, regiospecific, and stereoselective rROP.

Enantioselective Organocopper-Catalyzed Hetero Diels-Alder Reaction through Oxidation of Ethers into Enol Ethers.

We disclose a catalytic method for the enantio- and diastereoselective union of alkyl ethers and heterodienes. We demonstrate that a chiral Cu-BOX complex catalyzes the efficient oxidation of ethers into enol ethers in the presence of trityl acetate. Then, the organocopper promotes stereoselective hetero Diels-Alder reaction between the generated enol ethers and β,γ-unsaturated ketoesters, allowing for rapid access to an array of dihydropyran derivatives possessing three vicinal stereogenic centers.

Desymmetrization of unactivated bis-alkenes chiral Brønsted acid-catalysed hydroamination.

Although great success has been achieved in catalytic asymmetric hydroamination of unactivated alkenes using transition metal catalysis and organocatalysis, the development of catalytic desymmetrising hydroamination of such alkenes remains a tough challenge in terms of attaining a high level of stereocontrol over both remote sites and reaction centers at the same time. To address this problem, here we report a highly efficient and practical desymmetrising hydroamination of unactivated alkenes catalysed by chiral Brønsted acids with both high diastereoselectivity and enantioselectivity. This method features a remarkably broad alkene scope, ranging from mono-substituted and -/1,2-disubstituted to the challenging tri- and tetra-substituted alkenes, to provide access to a variety of diversely functionalized chiral pyrrolidines bearing two congested tertiary or quaternary stereocenters with excellent efficiency under mild and user-friendly synthetic conditions.

A Dual-Catalytic Strategy To Direct Asymmetric Radical Aminotrifluoromethylation of Alkenes.

A novel asymmetric radical aminotrifluoromethylation of alkenes has been developed for the first time, providing straightforward access to densely functionalized CF3-containing azaheterocycles bearing an α-tertiary stereocenter with excellent enantioselectivity. The key to success is not only the introduction of a Cu(I)/chiral phosphoric acid dual-catalytic system but also the use of urea with two acidic N-H as both the nucleophile and directing group. The utility of this method is illustrated by facile transformations of the products into other important compounds useful in organic synthesis and medicinal chemistry.