Enantioselective [3+2] Annulation of Aldimines with Alkynes by Scandium-Catalyzed C-H Activation.

The enantioselective [3+2] annulation of readily accessible aldimines with alkynes via C-H activation is, in principle, a straightforward and atom-efficient route for synthesizing chiral 1-aminoindenes, which are important components in a wide array of natural products, bioactive molecules, and functional materials. However, such asymmetric transformation has remained undeveloped to date due to the lack of suitable chiral catalysts. Here, we report for the first time the enantioselective [3+2] annulation of aldimines with alkynes via C-H activation using chiral half-sandwich scandium catalysts.

Selective Pyk2 inhibition enhances bone restoration through SCARA5-mediated bone marrow remodeling in ovariectomized mice.

Understanding the intricate cellular interactions involved in bone restoration is crucial for developing effective strategies to promote bone healing and mitigate conditions such as osteoporosis and fractures. Here, we provide compelling evidence supporting the anabolic effects of a pharmacological Pyk2 inhibitor (Pyk2-Inh) in promoting bone restoration. In vitro, Pyk2 signaling inhibition markedly enhances alkaline phosphatase (ALP) activity, a hallmark of osteoblast differentiation, through activation of canonical Wnt/β-catenin signaling.

()-Selective Isomerization of 1,1-Disubstituted Alkenes by Scandium-Catalyzed Allylic C-H Activation.

The isomerization of 1,1-disubstituted alkenes through 1,3-hydrogen shift is an atom-efficient route for synthesizing trisubstituted alkenes, which are important moieties in many natural products, pharmaceuticals, and organic materials. However, this reaction often encounters regio- and stereoselectivity challenges, typically yielding /-mixtures of the alkene products or thermodynamically favored ()-alkenes. Herein, we report the ()-selective isomerization of 1,1-disubstituted alkenes to trisubstituted ()-alkenes via the regio- and stereospecific activation of an allylic C-H bond.

Regio- and Diastereoselective Annulation of α,β-Unsaturated Aldimines with Alkenes via Allylic C(sp)-H Activation by Rare-Earth Catalysts.

The [3 + 2] or [4 + 2] annulation of α,β-unsaturated aldimines with alkenes via β'- or γ-allylic C(sp)-H activation is, in principle, an atom-efficient route for the synthesis of five- or six-membered-ring cycloalkylamines, which are important structural motifs in numerous natural products, bioactive molecules, and pharmaceuticals. However, such a transformation has remained undeveloped to date probably due to the lack of suitable catalysts. We report herein for the first time the regio- and diastereoselective [3 + 2] and [4 + 2] annulations of α,β-unsaturated imines with alkenes via allylic C(sp)-H activation by half-sandwich rare-earth catalysts having different metal ion sizes.