Highly Efficient Alkene Epoxidation and Aziridination Catalyzed by Iron(II) Salt + 4,4′,4′′-Trichloro-2,2′:6′,2′′-terpyridine/4,4′′-Dichloro-4′-O-PEG-OCH3-2,2′:6′,2′′-terpyridine

2,2,2-Trifluoroacetophenone: an organocatalyst for an environmentally friendly epoxidation of alkenes

A cheap, mild, fast, and environmentally friendly oxidation of olefins to the corresponding epoxides is reported using polyfluoroalkyl ketones as efficient organocatalysts. Namely, 2,2,2-trifluoroacetophenone was identified as an improved organocatalyst for the epoxidation of alkenes. Various olefins, mono-, di-, and trisubstituted, are epoxidized chemoselectively in high to quantitative yields utilizing 2-5 mol % catalyst loading and H2O2 as the green oxidant.

Rhodium-catalyzed regio- and stereoselective oxyamination of dienes via tandem aziridination/ring-opening of dienyl carbamates

The dual role of a Rh(ii) catalyst both as a nitrene transfer agent and as a Lewis acid in the aziridine ring opening allows the regio- and stereoselective oxyamination of dienyl carbamates.

Iron-catalyzed efficient intermolecular amination of C(sp3)–H bonds with bromamine-T as nitrene source

[Fe(N4Py)(CH₃CN)](ClO₄)₂ can efficiently catalyze intermolecular nitrene insertion of sp³ C–H bonds with bromamine-T as the nitrene source, forming the desired tosylprotected amines with NaBr as the by-product.

Iron-mediated C-H bond amination by organic azides on a tripodal bis(anilido)iminophosphorane platform

The bis(anilido)iminophosphorane complex, abbreviated as [((Mes)N2N(Ad))Fe(THF)], can react with alkyl azides to yield ligand-based C-H bond amination products suggesting the high reactivity of iron(IV)-imido species supported by the tripodal bis(anilido)iminophosphorane ligand platform [(Mes)N2N(Ad)](2-).

Nonheme iron-mediated amination of C(sp3)-H bonds. Quinquepyridine-supported iron-imide/nitrene intermediates by experimental studies and DFT calculations

The 7-coordinate complex [Fe(qpy)(MeCN)2](ClO4)2 (1, qpy = 2,2':6',2″:6″,2''':6''',2''''-quinquepyridine) is a highly active nonheme iron catalyst for intra- and intermolecular amination of C(sp(3))-H bonds. This complex effectively catalyzes the amination of limiting amounts of not only benzylic and allylic C(sp(3))-H bonds of hydrocarbons but also the C(sp(3))-H bonds of cyclic alkanes and cycloalkane/linear alkane moieties in sulfamate esters, such as those derived from menthane and steroids cholane and androstane, using PhI═NR or "PhI(OAc)2 + H2NR" [R = Ts (p-toluenesulfonyl), Ns (p-nitrobenzenesulfonyl)] as nitrogen source, with the amination products isolated in up to 93% yield. Iron imide/nitrene intermediates [Fe(qpy)(NR)(X)](n+) (CX, X = NR, solvent, or anion) are proposed in these amination reactions on the basis of experimental studies including ESI-MS analysis, crossover experiments, Hammett plots, and correlation with C-H bond dissociation energies and with support by DFT calculations. Species consistent with the formulations of [Fe(qpy)(NTs)2](2+) (CNTs) and [Fe(qpy)(NTs)](2+) (C) were detected by high-resolution ESI-MS analysis of the reaction mixture of 1 with PhI═NTs (4 equiv). DFT calculations revealed that the reaction barriers for H-atom abstraction of cyclohexane by the ground state of 7-coordinate CNTs and ground state of C are 15.3 and 14.2 kcal/mol, respectively, in line with the observed high activity of 1 in catalyzing the C-H amination of alkanes under mild conditions.

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.

Aziridines from intramolecular alkene aziridination of sulfamates: reactivity toward carbon nucleophiles. application to the synthesis of spisulosine and its fluoro analogue

Catalytic intramolecular alkene aziridination of sulfamate is an emerging methodology for the asymmetric synthesis of chiral functionalized amines involving the formation of bicyclic aziridines. This study demonstrates the ability of the latter to undergo ring-opening with various carbon nucleophiles: Grignard reagents, lithium salts of terminal alkynes, dithiane, malonate. These S(N)2-type reactions occur with high levels of regio- and chemoselectivity to generally afford seven-membered cyclic sulfamidates in good yields. Carbon nucleophiles have also been found to react with these sulfamidates provided that the sulfamate ester has been previously activated by introduction of a tosyl substituent on the NH group. The versatility of this strategy has been illustrated with the syntheses of spisulosine and its fluoro analogue.

Iron(II)-catalyzed amidation of aldehydes with iminoiodinanes at room temperature and under microwave-assisted conditions

A method for the amidation of aldehydes with PhI=NTs/PhI=NNs as the nitrogen source and an inexpensive iron(II) chloride + pyridine as the in situ formed precatalyst under mild conditions at room temperature or microwave assisted conditions is described. The reaction was operationally straightforward and accomplished in moderate to excellent product yields (20-99%) and with complete chemoselectivity with the new C-N bond forming only at the formylic C-H bond in substrates containing other reactive functional groups. By utilizing microwave irradiation, comparable product yields and short reaction times of 1 h could be accomplished. The mechanism is suggested to involve insertion of a putative iron-nitrene/imido group to the formylic C-H bond of the substrate via a H-atom abstraction/radical rebound pathway mediated by the precatalyst [Fe(py)(4)Cl(2)] generated in situ from reaction of FeCl(2) with pyridine.

Mechanism of the iron-mediated alkene aziridination reaction: experimental and computational investigations

Combined experimental and computational studies suggest that the iron-mediated aziridination of cis-1-phenylpropene proceeds along two mechanistic pathways that share a common imidoiron(IV) intermediate. One pathway involves a second species, proposed to be an azametallacyclobutane intermediate, which collapses to provide the syn-aziridine product. A second, parallel pathway is responsible for the formation of an anti-aziridine.