Synthesis of Tetrasubstituted Alkenes by Rhodium-Catalyzed Regioselective Cyano Transfer.

We describe herein a novel, general, and robust approach to structurally diversified alkenyl nitriles through a Rh-catalyzed cyano transfer reaction between alkynyl-malononitrile derivatives and aryl/alkenyl boronic acids. This reaction exhibits high chemo- and regioselectivity and a broad substrate scope. The tetrasubstituted alkenyl dinitriles (34 examples, average 58% yield) are obtained through substrate tuning and ligand control.

Chemo-divergent Cyano Group Migration: Involving Elimination and Substitution of the Key α-Thianthrenium Cyano Species.

Herein, we report a light-driven, radical-type cyano migration in the absence of a photocatalyst, enabling a chemo-divergent synthesis of (Z)-alkenyl nitriles and ketones. Trifluoromethyl thianthrenium salt (TT-CF3+OTf-) plays multiple roles: (a) absorbing light to generate trifluoromethyl radicals to initiate the reaction and (b) forming α-thianthrenium cyano species by in situ capture of TT• +. (Z)-Alkenyl nitriles were formed through the elimination of thianthrenium salts, and aryl ketones were obtained via the nucleophilic substitution of thianthrenium salts.

Copper-Catalyzed Synthesis of Quinoline-4-thiols from Diaryliodonium Salts, Alkynyl Sulfides, and Nitriles.

A three-component cascade cyclization catalyzed by copper was employed to synthesize quinoline-4-thiols using easily available diaryliodonium salts, alkynyl sulfides, and nitriles as starting materials. Sulfur atoms play an important role in controlling the regioselectivity, by stabilizing the high-valent vinyl copper intermediate. Meanwhile, the sulfide group at position 4 of quinoline could be further utilized as a transformable group for ipso-transformation and as a directing group for C-H functionalization, affording various multifunctional quinoline derivatives.

Stereocontrolled construction of six vicinal stereogenic centers on a hexahydroxanthone framework through a formal [2+1+3] annulation.

The first example of a bifunctional donor-donor 3C synthon in situ from activated methine (methyleneindolinone and methylenebenzofuranone) with nitromethane through a [2+1] Michael addition, which further directed the following organocascade Michael/Henry cycloaddition reaction in a one-pot operation is developed, serving as a fruitful strategy for facile access to optically active and structurally diverse hexahydroxanthones with up to six contiguous stereocenters, including a quaternary one. A series of diversely functionalized products are smoothly obtained with up to 76% yield, >20 : 1 d.r. and 98% ee from simple and readily available starting materials. In addition, this is the first example of 3-formyl chromone as an acceptor-acceptor 3C building block, and also the first asymmetric catalytic construction of six vicinal stereogenic centers on a hexahydroxanthone scaffold.