Pd(0)-catalyzed sequential C-N bond formation via allylic and aromatic C-H amination of α-methylstyrenes with diaziridinone

A novel Pd(0)-catalyzed sequential C-N bond formation process via allylic and aromatic C-H amination of α-methylstyrenes with di-tert-butyldiaziridinone, giving spirocyclic indolines in good yields, is described. Four C-N bonds and one spiro quaternary carbon are generated in a single operation.

Bis(sulfonylimide)ruthenium(VI) porphyrins: X-ray crystal structure and mechanism of C-H bond amination by density functional theory calculations

The X-ray crystal structure of [Ru(VI) (NMs)2 (tmp)] (Ms=SO2 - p-MeOC6 H4 ; tmp=5,10,15,20-tetramesitylporphyrinato(2-)), a metal sulfonylimide complex that can undergo alkene aziridination and C-H bond amination reactions, shows a Ru=N distance of 1.79(3) Å and Ru-N-S angle of 162.5(3)°. Density functional theory (DFT) calculations on the electronic structures of [Ru(VI) (NMs)2 (tmp)] and model complex [Ru(VI) (NMs)2 (por(0) )] (por(0) =unsubstituted porphyrinato(2-)) using the M06L functional gave results in agreement with experimental observations. For the amination of ethylbenzene by the singlet ground state of [Ru(VI) (NMs)2 (por(0))], DFT calculations using the M06L functional revealed an effectively concerted pathway involving rate-limiting hydrogen atom abstraction without a distinct radical rebound step. The substituent effect on the amination reactivity of ethylbenzene by [Ru(VI) (NX)2 (por(0) )] (X=SO2 -p-YC6 H4 with Y=MeO, Me, H, Cl, NO2 ) was examined. Electron-withdrawing Y groups lower the energy of the LUMOs of [Ru(VI) (NX)2 (por(0))], thus facilitating their interaction with the low-lying HOMO of the ethylbenzene C-H bond and hence increasing the reactivity of [Ru(VI) (NX)2 (por(0) )]. DFT calculations on the amination/aziridination reactions of [Ru(VI) (NSO2 C6 H5 )2 (por(0) )] with pent-4-enal, an aldehyde substrate bearing acyl, homoallylic, and allylic C-H bonds and a C=C bond, revealed a lower reaction barrier for the amination of the acyl C-H bond than for both the amination of the other C-H bonds and aziridination of the C=C bond in this substrate.

Chemoselective allene aziridination via Ag(I) catalysis

Allene aziridination generates useful bicyclic methylene aziridine scaffolds that can be flexibly transformed into a range of stereochemically complex and densely functionalized amine-containing stereotriads. The scope of this chemistry has been limited by the poor chemoselectivity that often results when typical dinuclear Rh(II) catalysts are employed with homoallenic carbamates. Herein, Ag(I) catalysts that significantly improve the scope and yield of bicyclic methylene aziridines that can be prepared via allene aziridination are described.

Transition-metal-catalyzed aminations and aziridinations of C-H and C=C bonds with iminoiodinanes

Catalytic insertion or addition of a metal-imido/nitrene species, generated from reaction of a transition-metal catalyst with iminoiodanes, to C-H and C=C bonds offers a convenient and atom economical method for the synthesis of nitrogen-containing compounds. Following this groundbreaking discovery during the second half of the last century, the field has received an immense amount of attention with a myriad of impressive metal-mediated methods for the synthesis of amines and aziridines having been developed. This review will cover the significant progress made in improving the efficiency, versatility and stereocontrol of this important reaction. This will include the various iminoiodanes, their in situ formation, and metal catalysts that could be employed and new ligands, both chiral and non-chiral, which have been designed, as well as the application of this functional group transformation to natural product synthesis and the preparation of bioactive compounds of current therapeutic interest.

Recent advances in transition metal-catalyzed sp3 C-H amination adjacent to double bonds and carbonyl groups

Transition metal-catalyzed C-H amination at positions adjacent to double bonds and carbonyl groups is discussed in this critical review. While the focus will center on the recent developments of α-oxidative amination, some historical developments and mutually beneficial reports in the broader field of C-H amination will be discussed. C-H amination has become a viable method for the efficient installation of nitrogen atoms en route to target molecules (89 references).

Development of versatile and silver-free protocols for gold(I) catalysis

The use of a versatile N-heterocyclic carbene (NHC) gold(I) hydroxide precatalyst, [Au(OH)(IPr)], (IPr=N,N'-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) permits the in situ generation of the [Au(IPr)](+) ion by simple addition of a Brønsted acid. This cationic entity is believed to be the active species in numerous catalytic reactions. (1)H NMR studies in several solvent media of the in situ generation of this [Au(IPr)](+) ion also reveal the formation of a dinuclear gold hydroxide intermediate [{Au(IPr)}(2)(μ-OH)], which is fully characterized and was tested in gold(I) catalysis.

A computational study of metal-mediated decomposition of nitrene transfer reagents

Metal-mediated decomposition to form nitrene complexes is investigated by using DFT for prototypical organic azides and iodonium imides used in organic synthesis. Each system exhibited exothermic pathways via formation of cyclic intermediates, which decompose to yield LNi = NX + Y (L = bis-phosphine, NX = nitrene, Y = N2 or IPh). Also, the typical heterotransfer reagents used in organic synthesis show a greater tendency toward triplet nitrene complexes and hence the potential for metal-free reactivity than aliphatic and aromatic substituted versions.

Practical copper(I)-catalysed amidation of aldehydes

The direct synthesis of amides by insertion into the C-H bond of aldehydes is shown to be a practical procedure through application of cheap, readily available catalysts generated in situ from copper(i) halides and pyridine.

Nitrene transfer reactions mediated by metallo-porphyrin complexes

Nitrene transfer reactions represent a useful methodology to synthesize in a few steps high added-value compounds used as organic intermediates. Herein, we describe the catalytic activity of metal porphyrin complexes in a wide range of reactions such as C-H hydrocarbon amination and olefin aziridination to synthesize nitrogen containing molecules. All the most important nitrene sources have been reviewed stressing the potentiality and limits of each one in the particular class of chemical transformation.

Silver-catalysed Doyle-Kirmse reaction of allyl and propargyl sulfides

The silver-catalysed Doyle-Kirmse reaction of propargyl and allyl sulfides with diazo compounds is disclosed. The carbon-carbon bond forming process proceeds with a range of substituents and functionality under mild conditions.

Silver-catalyzed [2,3]-rearrangement of halonium ylides derived from allyl and propargyl halides and alkyl diazoacetates

A silver(I) complex derived from a polyfluorinated tris(pyrazolyl)borate effectively catalyzes carbene transfer to allylic and propargylic halides, leading to the formation of alpha-haloacetate derivatives.