Substituents Regulate the Cyclization of Conjugated Alkynes to Accurately Construct Cyclo-(E)-[3]dendralenes.

Substituent-regulated cyclization of conjugated alkynes with acid catalysis was developed in this paper, and it provides a straightforward synthesis of cyclic-(E)-[3]dendralenes. Depending on the electronic effect of the aromatic ring pairing, a variety of phosphinyl quintuplet/hexa cyclo-[3]dendralenes with diverse substitution patterns are accessible, with good efficiency and high stereoselectivity. This self-cyclization process achieves the first precise construction of a phosphinylcyclo-(E)-[3]dendralene from conjugated alkynes to aromatization.

Secondary phosphine oxides stabilized Au/Pd nanoalloys: metal components-controlled regioselective hydrogenation toward phosphinyl (Z)-[3]dendralenes.

A series of gold/palladium nanoalloys stabilized by secondary phosphine oxides have been prepared for the first time. The nanocatalysts exhibit excellent regio- and chemo-selectivity in the hydrogenation of conjugated enynes, providing a mild and highly efficient way to access phosphinyl (Z) and (Z,Z)-[3]dendralenes.

Cascade Alkynylation and Highly Selective Hydrogenation Catalyzed by Binaphthyl-Palladium Nanoparticles Accessing Phosphinyl (Z)-[3]Dendralenes.

A cascade alkynylation and selective hydrogenation catalyzed by covalent binaphthyl-stabilized palladium nanoparticles has been established, providing a novel and highly efficient methodology for accessing Z and Z,Z-selective phosphinyl [3]dendralenes with broad functional group tolerance and good yields. This strategy achieves the first cascade reactions of alkynylation and hydrogenation with chemoselectivity modulated by catalyst loading.

Metal-Free Hydrogen Atom Transfer from Water: Expeditious Hydrogenation of N-Heterocycles Mediated by Diboronic Acid.

A hydrogenation of N-heterocycles mediated by diboronic acid with water as the hydrogen atom source is reported. A variety of N-heterocycles can be hydrogenated with medium to excellent yields within 10 min. Complete deuterium incorporation from stoichiometric D2 O onto substrates further exemplifies the H/D atom sources. Mechanism studies reveal that the reduction proceeds with initial 1,2-addition, in which diboronic acid synergistically activates substrates and water via a six-membered ring transition state.