Palladium-catalyzed intramolecular asymmetric hydrocyclopropanylation of alkynes: synthesis of cyclopropane-fused γ-lactams.

A palladium-catalyzed intramolecular asymmetric hydrocyclopropanylation of alkynes via C(sp3)-H activation has been developed for the synthesis of cyclopropane-fused γ-lactams. The presented strategy proceeds in a selective and 100% atom-economical manner. A range of cyclopropane-fused γ-lactams were prepared from readily available substrates in good yields and enantioselectivities with a chiral phosphoramidite ligand.

Palladium- and Brønsted acid-catalyzed enantio-, site- and E/Z-selective addition of alkylidenecyclopropanes with imines.

Transition-metal catalyzed functionalization of ACPs has been widely investigated in cycloaddition and 1,3-difunctionalization reactions. However, the transition metal catalyzed nucleophilic reactions of ACPs have rarely been reported. In this article, an enantio-, site- and E/Z-selective addition of ACPs with imines for the synthesis of dienyl substituted amines has been developed via palladium- and Brønsted acid co-catalysis. A range of synthetically valuable dienyl substituted amines were effectively prepared with good to excellent yields and excellent enantio- and E/Z-selectivities.

Copper-catalyzed 1,2-Borylacylation of 1,3-Enynes: synthesis of ß-Alkynyl ketones.

A copper catalyzed 1,2-borylacylation of 1,3-enynes with B2pin2 and acid chlorides has been developed. Using readily available 1,3-enynes, B2pin2 and acid chlorides as substrates, a range of highly functionalized α,α-disubstituted ß-alkynyl ketones were readily prepared under mild conditions in moderate to good yields. The borylacylated products can be easily derivatized to give several valuable structures. Notably, treatment of the products with NaBO3·4H2O provided 1,2-allenyl ketones, which is proposed to proceed via a retro-aldol process of the corresponding homopropargyl alcohols.