Ring Opening Of Aziridines Research Articles

Tetraethylammonium Tetraselenotungstate: A Versatile Selenium Transfer Reagent in Organic Synthesis

Organoselenium compounds have attracted intense research owing to their unique biological properties as well as pharmaceutical significance. Progress has been made in developing reagents for incorporation of selenium in an efficient and controlled manner. Herein, we present a review on the recently developed selenium reagent, tetraethylammonium tetraselenotungstate, [Et(4)N](2)WSe(4) as a versatile selenium transfer reagent in organic synthesis. Tetraselenotungstate has been successfully used for the synthesis of a number of functionalized diselenides, sugar- and nucleoside-derived diselenides, seleno-cystines, selenohomocystines, selenoamides, selenoureas and sugar- and nucleoside-based cyclic-selenide derivatives. Additionally, this reagent has been employed for the ring opening of aziridines to synthesize a variety of β-aminodiselenides. A new selena-aza-Payne type rearrangement of aziridinemethanoltosylates mediated by tetraselenotungstate for the synthesis of allyl amines is also discussed.

Highly regioselective ring-opening of aziridines with arenesulfinates on water: a facile access to β-amino/vinyl sulfones

We have developed a LiBr catalyzed efficient synthesis of β-amino sulfones from readily available aziridines and sodium sulfinates in good to excellent yields. The synthetic potential of β-amino sulfones has also been demonstrated by their facile conversion to the corresponding vinyl sulfones. The use of water as reaction media, atom-economy and isolation of products by simple filtration in the case of solid β-amino sulfones are certain green virtues of the synthetic protocol.

ChemInform Abstract: Modular Functionalization of Allenes to Aminated Stereotriads.

AbstractRhodium‐catalyzed cyclization of allenic sulfamate (I) provides access towards a strained bicyclic methylene aziridine intermediate, which undergoes aziridine ring opening on reaction with various nucleophiles to afford cyclic sulfamates (III).

Synthesis of Oxindole-Appended Allyl Amines and Vinyl Aziridines via InCl3/ArSH-Mediated Ring Opening of Vinyl Aziridines and Sulfur Ylide Aziridination

A short and efficient synthesis of oxindole-appended allyl amines and 3-vinylaziridine-2-oxindoles have been accomplished in good yield via InCl3/ArSH-mediated ring opening of 3-vinylaziridine-2-oxindoles and sulfur ylide aziridination, respectively. The sulfur ylide was generated in situ from the bromo isomerized Morita–Baylis–Hillman adduct of isatin with N-tosyl imines and tetrahydrothiophene under basic conditions.

DNA adduct formation of mitomycin C. A test case for DFT calculations on model systems

Mitomycin C is a DNA alkylating agent activated by bioreduction. It has been in clinical use against a range of solid tumours since the 1960s. Its DNA adduct formation mechanism has been extensively studied and it therefore presents an excellent test case for the applicability of Density Functional Theory (DFT) calculations based on simple model systems. The reaction cascades proposed in the literature were calculated and the results revealed that many of the mechanistic features were correctly predicted: the one- and two-electron reduction was deemed plausible, the pH-dependence of the rate of aziridine ring opening, and that the alkylating agent is required to be formed in the proximity of DNA for adduct formation to occur. The DFT method was unable to predict where adduct formation takes place on the guanine based on the exothermicity of the nucleophilic attack. Overall, the DFT method does well to predict the mechanism for adduct formation considering that the model systems are simple and modest CPU requirements.

Straightforward synthesis of non-natural chalcogen peptides via ring opening of aziridines

The synthesis of new chiral non-natural seleno-, thio-, and telluro-peptides is described herein. These new compounds were prepared through simple and brief synthetic route, from inexpensive and commercially available amino acids. The products, possessing a highly modular character, were obtained in good to excellent yields (50–96%), via ring opening of aziridines with chalcogenolate anions, generated using indium(I) iodide as a reducing agent.

Domino aziridine ring opening and Buchwald–Hartwig type coupling-cyclization by palladium catalyst

Highly important trans-3,4-dihydro-2H-1,4-benzoxazine moieties were easily synthesized by domino aziridine ring opening with o-bromophenols and o-chlorophenols followed by the palladium catalyzed coupling-cyclization (intramolecular C(aryl)–N(amide) bond formation) with good to excellent yields.

Efficient Synthesis of α,β-Diamino Acid Derivatives by In(III)-Catalyzed Regioselective Addition of Amines to Aziridines

An efficient catalytic method for the synthesis of α, β-diamino acid derivatives has been developed via regioselective ring opening of aziridines by amines in the presence of indium(III) salt under very mild reaction conditions. Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file.

Asymmetric Ring Opening of Aziridines with Halides

Asymmetric Ring Opening of Aziridines with Halides

ZrCl4-Catalyzed Synthesis of β-Aminosulfides from Aziridines and Thiols

A simple and efficient synthesis of β-aminosulfides has been introduced by ring opening of aziridine rings with aromatic thiols in the presence of zirconium(IV) chloride under solvent-free conditions at room temperature.

Aziridines in Formal [3+2] Cycloadditions: Synthesis of Five‐Membered Heterocycles

AbstractChemistry based on ring opening of aziridines has been widely studied in organic synthesis. However, it has mainly been centered on ring opening by nucleophiles and on cycloaddition of azomethine ylides generated by carbon–carbon bond cleavage. In recent years, significant effort has been dedicated to study of the participation of aziridines in formal [3+2] cycloadditions, which provide routes for the construction of a wide variety of functionalized five‐membered heterocycles. Here we review the most relevant aspects of the reactivities and selectivities of aziridines as masked zwitterionic 1,3‐dipoles generated through C–N bond cleavage.

3,4-Dihydroxypyrrolidines via Modified Tandem Aza-Payne/Hydroamination Pathway

The outcome of a tandem aza-Payne/hydroamination reaction is modified via the use of a latent nucleophile. The latter initially serves as an electrophile to intercept the aziridine alkoxide and afterward turns into a nucleophile thereby performing the aziridine ring opening, out competing the intramolecular aza-Payne pathway. Subsequent hydroamination in the same pot provides N-Ts enamide carbonates, which can be easily converted into biologically significant 3,4-dihydroxylactams.

Conformational Modulation of in Vitro Activity of Cyclic RGD Peptides via Aziridine Aldehyde-Driven Macrocyclization Chemistry

Here, we demonstrate a conjugation strategy whereby cyclic RGD-containing macrocycles are prepared using aziridine aldehydes, isocyanides, and linear peptides, followed by conjugation to a cysteamine linker. Our method involves site-selective aziridine ring-opening with the nucleophilic sulfhydryl group of cysteamine. Fluorescein was then efficiently conjugated to the primary amine of cysteamine by NHS-chemistry. This strategy may be expanded to provide easy access to a wide variety of fluorescent dyes or radiometal chelators. Modeling studies showed that aziridine aldehyde cyclization chemistry stabilized the RGD motif into the required bioactive conformation and that this cyclization chemistry modulated the geometry of macrocycles of different residue lengths. In vitro studies showed that cPRGDA and cPRGDAA both selectively bound to α(V)β(3)-overexpressing U87 glioblastoma cells, and that cPRGDA had a better binding affinity compared to cPRGDAA. The improved binding affinity of cPRGDA was attributed to the fixed Pro-C(α)-Asp-C(α) distance surrounding the stabilized RGD motif in cPRGDA.

Tri-n-butylphosphane catalyzed ring opening of aziridines with secondary amines

Abstract Ring opening of aziridine with dialkyl amine took place readily in the presence of catalytic amounts of tri- n -butylphosphane (10 mol%) in the mixture of CH 3 CN/H 2 O (10:1), giving corresponding vicinal diamines in mediate to high yields (58–95%) with good regioselectivitie, while aromatic secondary amine could not react under the same conditions. Tri- n -butylphosphane exhibited different catalytic selectivity to amines from Lewis acid catalysts.

Alkylative Ring Opening of Chiral Aziridines

Alkylative Ring Opening of Chiral Aziridines

Efficient and regioselective ring-opening of arylaziridines with alcohols, thiols, amines and N-heteroaromatic compounds using sulphated zirconia

Sulphated zirconia is an efficient catalyst for the regioselective ring-opening of aryl-substituted aziridines. This heterogeneous catalyst can be used several times without loss of activity and is compatible with a variety of acid sensitive and slightly basic nucleophiles.

Regioselectivity in the ring opening of non-activated aziridines

In this critical review, the ring opening of non-activated 2-substituted aziridines via intermediate aziridinium salts will be dealt with. Emphasis will be put on the relationship between the observed regioselectivity and inherent structural features such as the nature of the C2 aziridine substituent and the nature of the electrophile and the nucleophile. This overview should allow chemists to gain insight into the factors governing the regioselectivity in aziridinium ring openings (81 references).

Facile synthesis of 2-pyrazolines and α,β-diamino ketones via regioselective ring-opening of hydrazone-tethered aziridines

A facile strategy to access 2-pyrazolines and α,β-diamino ketones via SN(2)-type ring-opening of N-(aziridin-2-ylethylidene)hydrazines or N-(aziridin-2-ylbutylidene)hydrazines in the presence of Lewis acid or trifluoromethanesulfonic acid (TfOH) is described in this context.

Cationic Late-Transition-Metal Complexes Catalyze the Ring Opening of Aziridines with Amines

Cationic palladium and nickel complexes have been found to catalyze the ring-opening of meso-N-aryl aziridines with anilines very efficiently and furnish valuable 1,2-diamines in typically excellent yields. The active catalysts were generated in situ from the corresponding metal dichloride bis(triphenylphosphine) complexes through chloride abstraction with a silver salt. This new protocol is applicable across a broad substrate range with both cyclic as well as acyclic aziridines. In addition, cationic gold-phosphine complexes proved to be highly reactive as well as delivering products in comparable rates and yields.

S N 2-type ring opening of substituted-N-tosylaziridines with zinc (II) halides: Control of racemization by quaternary ammonium salt

Quaternary ammonium salt mediated highly regioselective ring opening of aziridines with zinc(II) halides to racemic and non-racemic β-halo amines in excellent yield and selectivity is described. The reaction proceeds via an SN2-type pathway and the partial racemization of the starting substrate and the product was effectively controlled by using quaternary ammonium salts to afford the enantioenriched products (er up to 95:5). Quaternary ammonium salt mediated highly regioselective ring opening of aziridines with zinc(II) halides to racemic and non-racemic β-halo amines in excellent yield and selectivity is described.