Heteroaromatic Tosylates as Electrophiles in Regioselective Mizoroki–Heck‐Coupling Reactions with Electron‐Rich Olefins

Easy and direct : Regioselective Mizoroki–Heck‐coupling reactions using heteroaromatic tosylates as electrophiles were achieved, thus providing direct and easy access to highly functionalized α‐heteroarylvinyl amides and ethers.

     

Aerobic and Electrochemical Oxidative Cross‐Dehydrogenative‐Coupling (CDC) Reaction in an Imidazolium‐Based Ionic Liquid

The ionic liquid 1‐butyl‐3‐methylimidazolium tetrafluoroborate [BMIm][BF₄] has demonstrated high efficiency when applied as a solvent in the oxidative nitro‐Mannich carbon? carbon bond formation. The copper‐catalyzed cross‐dehydrogenative coupling (CDC) between N‐phenyltetrahydroisoquinoline and nitromethane in [BMIm][BF₄] occurred with high yield under the described reaction conditions. Both the ionic liquid and copper catalyst were recycled nine times with almost no lost of activity. The electrochemical behavior of the tertiary amine substrate and β‐nitroamine product was investigated employing [BMIm][BF₄] as electrolyte solvent. The potentiostatic electrolysis in ionic liquid afforded the desired product with a high yield. This result and the cyclic voltammetric investigation provide a better understanding of the reaction mechanism, which involves radical and iminium cation intermediates.     

Palladium‐Catalyzed Insertion of α‐Diazoesters into Vinyl Halides To Generate α,β‐Unsaturated γ‐Amino Esters

As easy as 1, 2, 3 : A palladium‐catalyzed three‐component coupling generates α,β‐unsaturated γ‐amino acids in a single step (see scheme). The reaction is believed to involve migration of a vinyl substituent to a highly electrophilic palladium carbene. Unlike previous synthetic approaches, this synthesis provides access to γ‐amino acids with non‐natural side chains.

     

Functional‐Group‐Tolerant Catalytic Migratory Oxidative Coupling of Nitrones

A copper‐catalyzed migratory oxidative‐coupling reaction between nitrones and various ethers/amines exhibited high functional‐group tolerance. Even in aqueous media, the reaction proceeded efficiently. For practical use of this catalysis, a unique sequential Huisgen cycloaddition was demonstrated. Mechanistic investigations revealed that the reaction proceeded through oxidative catalytic activation of ethers/amines to afford iminium/oxonium intermediates by concurrent dual one‐electron abstractions by copper(II) and oxyl radicals.