Catalytic Aminium Radical-Cation Salt (Magic Blue)-Initiated SN2-Type Nucleophilic Ring-Opening Transformations of Aziridines

A simple and atom economic protocol for the construction of C-X/C-C bonds via catalytic aminium radical-cation salt (Magic Blue)-initiated SN2-type nucleophilic ring-opening transformations of racemic and nonracemic aziridines with different hetero and carbon nucleophiles to afford various amino ethers, thioethers, and amines in up to 99% yield, and with perfect enantiospecificity for some substrates but reduced ee with others (for nonracemic aziridines), is developed. This aminium radical-cation salt-initiated, SN2-type nucleophilic ring-opening strategy, along with various cyclization protocols, is employed to synthesize various biologically significant compounds.

Nitrene-Mediated Enantioselective Intramolecular Olefin Oxyamination to Access Chiral γ-Aminomethyl-γ-Lactones

Attaching a nitrene precursor to an intramolecular nucleophile allows for a catalytic asymmetric intramolecular oxyamination of alkenes in which the nucleophile adds in an endocyclic position and the amine in an exocyclic fashion. Using chiral-at-ruthenium catalysts, chiral γ-aminomethyl-γ-lactones containing a quaternary carbon in γ-position are provided in high yields (up to 99 %) and with excellent enantioselectivities (up to 99 % ee). DFT calculations support the possibility of both a singlet (concerted oxyamination of the alkene) and triplet pathway (stepwise oxyamination) for the formation of the predominant stereoisomer. γ-Aminomethyl-γ-lactones are versatile chiral building blocks and can be converted to other heterocycles such as δ-lactams, 2-oxazolidinones, and tetrahydrofurans.

Synthesis of Unprotected β-Arylethylamines by Iron(II)-Catalyzed 1,2-Aminoarylation of Alkenes in Hexafluoroisopropanol

β-Arylethylamines are prevalent structural motifs in molecules exhibiting biological activity. Here we report a sequential one-pot protocol for the 1,2-aminoarylation of alkenes with hydroxylammonium triflate salts and (hetero)arenes. Unlike existing methods, this reaction provides a direct entry to unprotected β-arylethylamines with remarkable functional group tolerance, allowing key drug-oriented functional groups to be installed in a two-step process. The use of hexafluoroisopropanol as a solvent in combination with an iron(II) catalyst proved essential to reaching high-value nitrogen-containing molecules.

Branching out: redox strategies towards the synthesis of acyclic α-tertiary ethers

Acyclic α-tertiary ethers represent a highly prevalent functionality, common to high-value bioactive molecules, such as pharmaceuticals and natural products, and feature as crucial synthetic handles in their construction. As such their synthesis has become an ever-more important goal in synthetic chemistry as the drawbacks of traditional strong base- and acid-mediated etherifications have become more limiting. In recent years, the generation of highly reactive intermediates via redox approaches has facilitated the synthesis of highly sterically-encumbered ethers and accordingly these strategies have been widely applied in α-tertiary ether synthesis. This review summarises and appraises the state-of-the-art in the application of redox strategies enabling acyclic α-tertiary ether synthesis.

Synthesis of substituted anilines via a gold-catalyzed three-component reaction

A three-component reaction for the synthesis of substituted anilines by a gold(i)-catalyzed domino reaction was developed.

Cp*Co(III)-Catalyzed C-7 C-C Coupling of Indolines with Aziridines: Merging C-H Activation and Ring Opening

A Cp*Co(III)-catalyzed directing group-assisted C7 C-C coupling of indolines with aziridines has been developed by merging C-H activation and ring opening. The use of cobalt catalyst, detection of a Co(III) intermediate, and late-stage removal of the directing group are important practical features.