A radical cyclization and ring-opening of oxime esters with diselenides was developed. Both Ni(0) and Fe(II) catalysts could be employed for the selenylation of olefin-containing and cyclic oxime ester derivatives. With this method, a variety of functionalized pyrrolines and alkyl nitriles were synthesized in good yields. Moreover, a mechanism involving iminyl radical and carbon-centered radical intermediates was proposed.

A one-pot approach to fluorinated hydroxamic acid, amide, and thioamide derivatives is reported. The reaction proceeds via an N-perfluoroalkylation of nitrosoarenes with perfluoroalkanesulfinates, resulting in labile N-perfluoroalkylated hydroxylamines. By the addition of suitable additives, a controllable oxy/thiodefluorination of the fluorinated hydroxylamine intermediates was achieved. The method highlights N-perfluoroalkylated amines as versatile intermediates for further synthesis.

A diastereoselective metal-catalyzed reaction of 2-(2-enynyl)pyridines and cyclic enamines is reported. The method provides access to a variety of substituted indolizine derivatives by variation of the enyne component and the reaction conditions. Performing the reaction using a preformed enamine led to the formation of polycyclic indolizines. With in situ generated enamines, ketone-containing indolizine derivatives were obtained. An asymmetric reaction of 2-(2-enynyl)pyridines and enamines generated from an aldehyde and a catalytic amount of amine is presented.

A redox-economical strategy for the synthesis of trifluoromethylated enamides using copper catalysis is reported. The reaction employs the inexpensive Langlois reagent (CF3SO2Na) and takes place without the need of an external oxidant. The trifluoromethylated enamide products can easily be converted into the corresponding ketone, saturated amide or oxazole.

An iron-catalyzed coupling reaction of O-acyloximes and O-benzoyl amidoximes with silyl enol ethers is reported. The protocol provides access to functionalized pyrroles, 1,6-ketonitriles, pyrrolines and imidazolines via carbon-centered radicals generated from an initially formed iminyl radical. The intramolecular cyclization and ring-opening processes of the iminyl radical take place preferentially over reactions that proceed through a 1,3-hydrogen transfer, providing insights into iron-catalyzed reactions with oxime derivatives. The cheap and environmentally friendly iron catalyst, the broad substrate scope and the functional group compatibility make this protocol useful for synthesis of valuable nitrogen-containing products.

The use of a well-chosen catalyst is instrumental for the development of more efficient, economical and environmentally friendly reactions. In recent decades, indium-based catalysts have proven to be competitive and useful alternatives to transition-metal catalysts such as silver and gold. In this short review, we present some of the recent advances in indium(III)-catalyzed transformations of alkynes, with a focus on cyclization reactions. 1 Introduction 2 Terminal Alkynes as Nucleophiles 3 Nucleophilic Additions to Alkynes 4 Carbo- and Heterocyclization Reactions 4.1 Carbocyclization 4.2 Oxygen-Based Heterocycles 4.3 Nitrogen-Based Heterocycles 4.4 Sulfur-Based Heterocycles 5 Conclusion

A nickel-catalyzed 1,2-aminoarylation of oximeester-tethered alkenes with boronic acids was developed. A variety of pyrroline derivatives were synthesized in good yields via the successive formation of C(sp(3))-N and C(sp(3))-C(sp(2)) bonds. For cyclobutanone-derived oxime esters, the reaction provided aliphatic nitriles incorporating an aromatic group in the gamma-position. A mechanism involving iminyl radical and carbon-centered radical intermediates was proposed.

A highly efficient N-trifluoromethylation of nitro-soarenes is reported. The inexpensive and convenient Langlois reagent (sodium triflinate) is employed as a Ch(3)-radical source in combination with a copper catalyst and an oxidant. N-Trifluoromethylated hychoxylamines are obtained in high yields within 1 h at room temperature. The addition of hydroquinone was found to be instrumental to prevent the formation of side products. The method is high-yielding is scalable, and displays a high functional group tolerance.

An intermolecular cyclization of alkynyl enones with cyclic ketones for the synthesis of bicyclo[3.n.1]alkenones is reported. This protocol exhibits a high functional group tolerance and provides access to a variety of bicyclic systems found as skeletons in many natural products.

A diastereoselective three-component reaction between alkynyl enones, aldehydes and secondary amines is reported. With the aid of a benign indium catalyst, a range of highly substituted cyclopenta[c]furan derivatives can be obtained in a single-step procedure. The formation of the stereodefined heterocyclic motifs takes place via in situ generation of enamines followed by two sequential cyclization steps.