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The enantioselective transformation of easily accessible 1,2-diketones represents a quick pathway towards enantioenriched molecules. Herein, we disclose a copper-catalyzed atroposelective formal [4+1] annulation of 1,2-diketones with vinyl cations, enabling the efficient and atom-economical construction of axially chiral arylpyrroles bearing 1,3-dioxole moieties with good to excellent enantioselectivities under mild reaction conditions. Importantly, this methodology constitutes the first enantioselective formal [4+1] annulation of 1,2-diketones. [ABSTRACT FROM AUTHOR]

In recent years, asymmetric catalysis of ynamides has attracted much attention, but these reactions mostly constructed central chirality, except for a few examples on the synthesis of axially chiral compounds which exclusively relied on noble‐metal catalysis. Herein, a facile access to axially chiral N‐heterocycles enabled by chiral Brønsted acid‐catalyzed 5‐endo‐dig cyclization of ynamides is disclosed, which represents the first metal‐free protocol for the construction of axially chiral compounds from ynamides. This method allows the practical and atom‐economical synthesis of valuable N‐arylindoles in excellent yields with generally excellent enantioselectivities. Moreover, organocatalysts and ligands based on such axially chiral N‐arylindole skeletons are demonstrated to be applicable to asymmetric catalysis. [ABSTRACT FROM AUTHOR]

Ynamides are electron‐rich heteroatom‐substituted alkynes with C−C triple bond directly tethered to the amide group. Over the past decades, ynamides have proven to be versatile reagents for organic synthesis and have received extensive attention. Compared with the well‐established ionic reactions of ynamides, radical‐based ynamide reactions have been exploited relatively seldom. Herein, radical reactions of ynamides, classified by radical attack at the α‐position and β‐position of ynamides, are reviewed by highlighting the reaction selectivity, scope, mechanism, and applicability. The aim of this review is to provide a comprehensive summarization of these advances, casting light on the further development of ynamide chemistry. [ABSTRACT FROM AUTHOR]

6π electrocyclization has attracted interest in organic synthesis because of its high stereospecificity and atom economy in the construction of versatile 5–7‐membered cycles. However, examples of asymmetric 6π electrocyclization are quite scarce, and have to rely on the use of chiral organocatalysts, and been limited to pentadienyl‐anion‐ and triene‐type 6π electrocyclizations. Described herein is a zinc‐catalyzed formal [4+3] annulation of isoxazoles with 3‐en‐1‐ynol ethers via 6π electrocyclization, leading to the site‐selective synthesis of functionalized 2H‐azepines and 4H‐azepines in good to excellent yields with broad substrate scope. Moreover, this strategy has also been used to produce chiral 2H‐azepines with high enantioselectivities (up to 97:3 e.r.). This protocol not only is the first asymmetric heptatrienyl‐cation‐type 6π electrocyclization, but also is the first asymmetric reaction of isoxazoles with alkynes and the first asymmetric catalysis based on ynol ethers. [ABSTRACT FROM AUTHOR]

With increasing interest in constructing more three-dimensional entities, there has been growing interest in cross-coupling reactions that forge C(sp 3 )-C(sp 3 ) bonds, which leads to additional challenges as it is not just a more difficult bond to construct but issues of stereocontrol also arise. Herein, we report the stereocontrolled cross-coupling of enantioenriched boronic esters with racemic allylic carbonates enabled by iridium catalysis, leading to the formation of C(sp 3 )-C(sp 3 ) bonds with single or vicinal stereogenic centers. The method shows broad substrate scope, enabling primary, secondary, and even tertiary boronic esters to be employed, and can be used to prepare any of the four possible stereoisomers of a coupled product with vicinal chiral centers. The new method, which combines the simultaneous enantiospecific reaction of a chiral nucleophile with the enantioselective reaction of a chiral electrophile in a single process, offers a solution for stereodivergent cross-coupling of two C(sp 3 ) fragments.