Aziridination Reaction Research Articles

Iron‐Catalyzed Aziridination Reactions

AbstractA small quantity of iron(II) triflate (2.5 to 5 mol%) catalyzes the aziridination reactions of enol silyl ethers with tosylimino(iodo)benzene (PhINTs) in acetonitrile to give α‐N‐tosylamido ketones by subsequent aziridine ring opening. Olefins are converted into aziridines by 5 mol% of this catalyst system. Both reactions afford the corresponding products in moderate to good yields. In the presence of chiral ligands asymmetric aziridinations have been achieved.

ChemInform Abstract: A Thiacalix[3]pyridine Copper(I) Complex as a Highly Active Catalyst for the Olefin Aziridination Reaction.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Allylic Amination and Aziridination of Olefins by Aryl Azides Catalyzed by CoII(tpp): A Synthetic and Mechanistic Study

AbstractCoII(tpp) catalyzes the reaction of aromatic azides (ArN3) with nonactivated olefins to yield allylic amines or aziridines in moderate‐to‐good yields. The chemoselectivity of the catalytic reaction is particularly high. Depending on the substrate employed, allylic amines or aziridines can be obtained. The reaction mechanism was investigated, and the reaction proceeds through reversible coordination of the aryl azide to the CoII–porphyrin complex. The often postulated “nitrene” complex is not an intermediate in this reaction. The kinetics for the allylic amination is first order in azide, Co(tpp), and olefin. For the aziridination, the kinetics is again first order in azide and catalyst, but we observed a first‐order dependence of the rate on α‐methylstyrene only up to an olefin concentration of 6.9 M. An inhibiting role of the competitively formed 1‐(4‐nitrophenyl)‐5‐methyl‐5‐phenyl‐1,2,3‐triazoline was identified. The triazoline was shown to reversibly coordinate to Co(tpp), which blocks the free coordination site necessary for the catalytic reaction to proceed, and is it responsible for the catalyst deactivation in the aziridination reaction of α‐methylstyrene by 4‐nitrophenyl azide. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

ChemInform Abstract: Dramatic Effects of Halogen Substitution and Solvent on the Rates and Mechanisms of Nucleophilic Substitution Reactions of Aziridines.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Quaternary Ammonium Bromide Functionalized Polyethylene Glycol: A Highly Efficient and Recyclable Catalyst for Selective Synthesis of 5-Aryl-2-oxazolidinones from Carbon Dioxide and Aziridines Under Solvent-Free Conditions

A quaternary ammonium bromide covalently bound to polyethylene glycol (PEG, MW = 6000), i.e., PEG(6000-)(NBu(3)Br)2, was found to be an efficient and recyclable catalyst for the cycloaddition reaction of aziridines to CO(2) under mild conditions without utilization of additional organic solvents or cocatalysts. As a result, 5-aryl-2-oxazolidinone was obtained in high yield with excellent regioselectivity. The catalyst worked well for a wide variety of 1-alkyl-2-arylaziridines. Besides, the catalyst could be recovered by centrifugation and reused without significant loss of catalytic activity and selectivity.

A Concise Synthesis of (−)‐Oseltamivir

Tackling the supply problem: A short and efficient synthesis of (−)-oseltamivir has been developed which requires eight steps from commercially available starting material and proceeds with an overall yield of 30 %. Key transformations include a novel palladium-catalyzed asymmetric allylic alkylation reaction (Pd-AAA, see scheme) as well as a chemo-, regio-, and stereoselective aziridination reaction. Phth=phthaloyl.

Catalytic Asymmetric Aziridination with Borate Catalysts Derived from VANOL and VAPOL Ligands: Scope and Mechanistic Studies

An extended study of the scope and mechanism of the catalytic asymmetric aziridination of imines with ethyl diazoacetate mediated by catalysts prepared from the VANOL and VAPOL ligands and triphenylborate is described. Nonlinear studies with scalemic VANOL and VAPOL reveal an essentially linear relationship between the optical purity of the ligand and the product suggesting that the catalyst incorporates a single molecule of the ligand. Two species are present in the catalyst prepared from B(OPh)(3) and either VANOL or VAPOL as revealed by (1)H NMR studies. Mass spectral analysis of the catalyst mixture suggests that one of the species involves one ligand molecule and one boron atom (B1) and the other involves one ligand and two boron atoms (B2). The latter can be formulated as either a linear or cyclic pyroborate and the (11)B NMR spectrum is most consistent with the linear pyroborate structure. Several new protocols for catalyst preparation are developed which allow for the generation of mixtures of the B1 and B2 catalysts in ratios that range from 10:1 to 1:20. Studies with catalysts enriched in the B1 and B2 species reveal that the B2 catalyst is the active catalyst in the VAPOL catalyzed asymmetric aziridination reaction giving significantly higher asymmetric inductions and rates than the B1 catalyst. The difference is not as pronounced in the VANOL series. A series of 12 different imines were surveyed with the optimal catalyst preparation procedure with the finding that the asymmetric inductions are in the low to mid 90s for aromatic imines and in the mid 80s to low 90s for aliphatic imines for both VANOL and VAPOL catalysts. Nonetheless, the crystallinity of the N-benzhydryl aziridines is such that nearly all of the 12 aziridine products screened can be brought to >99 % ee with a single recrystallization.

A Thiacalix[3]pyridine Copper(I) Complex as a Highly Active Catalyst for the Olefin Aziridination Reaction

Abstract A copper(I) complex with thiacalix[3]pyridine, [Cu(Py3S3)]2(PF6)2, is a competent catalyst for aziridination of olefins. The reaction of styrene (1 equiv) with PhI=NTs (1 equiv) at 20 °C produced N-(p-toluenesulfonyl)-2-phenylaziridine (71%, turnover number = 55) in the presence of 1.2 mol % catalyst under aerobic conditions. The turnover number increased up to 350 with a 0.12 mol % catalyst and a 5:1 styrene/PhI=NTs ratio in 41% yield.

Dramatic Effects of Halogen Substitution and Solvent on the Rates and Mechanisms of Nucleophilic Substitution Reactions of Aziridines

In a previous study we reported that fluorine substitution at the carbon positions of aziridine results in profound enhancements of the rate of reaction with ammonia, a typical nucleophile, in the gas phase. In this study the investigation is extended to include chloro- and bromoaziridines. Because syntheses are largely performed in the condensed phase, the present computational investigation [(MP2(Full)/6-311++G(d,p)//MP2(Full)/6-31+G(d) level] was conducted with three typical solvents that cover a wide range of polarity: THF, CH3CN, and H2O. Nucleophiles can react with haloaziridines 1 by displacing a substituted amide ion by means of an SN2 mechanism (pathway a), producing 1,2-diaminohaloethanes (from the initially formed dipolar species 2). Alternatively, a rearrangement mechanism involving rate-determining departure of a halide ion (pathway b) to form an imidoyl halide, 3, is possible. Transition-state theory was used to compute relative reaction rates of these mechanistic possibilities and to assess the role of the halogen substituents and the reaction solvent. Gas-phase results provided the basis of mechanistic insights that were more apparent in the absence of intermolecular interactions. Fluoroaziridines were found to react at accelerated rates relative to aziridine exclusively by means of the a Menshutkin-type mechanism (SN2) in each solvent tested, while the reactions of the chloro- and bromoaziridines could be directed toward 2 in the highly nonpolar solvent, cyclohexane, or toward 3 in the more polar solvents. An assessment is made of the feasibility of using this chemistry of the haloazirdines in the synthetic laboratory.

ChemInform Abstract: Tri‐n‐butylphosphine Mediated Ring‐Opening Reactions of Aziridines or Epoxides with Diphenyl Diselenide.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

A New Strategy for the Synthesis of 1,4-Benzodiazepine Derivatives Based on the Tandem N-Alkylation−Ring Opening−Cyclization Reactions of Methyl 1-Arylaziridine-2-carboxylates with N-[2-Bromomethyl(phenyl)]trifluoroacetamides

A new method for the synthesis of novel 1,4-benzodiazepine derivatives has been established from a one-pot reaction of methyl 1-arylaziridine-2-carboxylates with N-[2-bromomethyl(aryl)]trifluoroacetamides. The reaction proceeds through the N-benzylation and highly regioselective ring-opening reaction of aziridine by bromide anion followed by Et3N-mediated intramolecular nucleophilic displacement of the bromide by the amide nitrogen. The easy availability of starting materials, simple and convenient synthetic procedure, and formation of functionalized 1,4-benzodiazepine scaffold ready for further chemical manipulations render this strategy useful in synthetic and medicinal chemistry.

Stereoselective aza-MIRC reactions on optically active ( E)-nitro alkenes

Optically active ( E)-nitro alkenes carrying a 1,3-dioxolane or 1,3-oxazolidine residue undergo stereoselective aza-MIRC reactions, leading to the synthesis of the corresponding chiral nitro aziridines in high yields and with good diastereoselectivity. Interestingly, the stereochemical outcome of the aziridination reactions was strongly influenced by the chiral residue considered, giving stereoisomers, regardless of the reaction conditions.

A Synthesis of 6-Azabicyclo[3.2.1]octanes. The Role of N-Substitution

The intramolecular cyclization reactions of aziridines with pi-nucleophiles can be a useful route to a number of heterocyclic and carbocyclic ring systems. We were particularly interested in the use of this cyclization reaction for the synthesis of 6-azabicyclo[3.2.1]octanes. We report here the development of a new synthesis of the aziridine necessary for the aziridine--pi-nucleophile cyclization. We also report on the cyclization of aziridines with three different substitutions on the aziridine nitrogen. We have found that N-diphenylphospinyl and N-H aziridines, while participating in the initial ring-opening reaction, do not lead to the desired bicyclic ring systems. In contrast, a nosyl group on the aziridine nitrogen leads efficiently to the bicyclic ring system and can be readily deprotected.

ChemInform Abstract: Gold(III) Chloride/Silver Triflate: A Highly Efficient Catalyst for Ring‐Opening Reaction of Aziridines with Electron‐Rich Arenes.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Iron-catalysed aziridination reactions promoted by an ionic liquid

A catalytic system based on iron(II) triflate, quinaldic acid and an ionic liquid allows the aziridination of olefins with equimolar amounts of iminoiodinane providing products in good to moderate yields.

Heterogenization of ruthenium porphyrin complexes in polymeric membranes: Catalytic aziridination of styrenes

In this paper we report the preparation of catalytic membranes having the complex Ru(4-(CF 3)TPP)CO ( 1) (TPP = dianion of tetraphenylporphyrin) embedded in the perfluorinated polymer Hyflon AD60X and their use in the aziridination reaction of olefins by aryl azides. The heterogeneous membrane catalysts afforded high selectivities in aziridine (90–99%). In several cases the membrane was reused three times with a catalyst leaching ≤6% but no decrease in selectivities upon recycle was observed.

Arylbutyltellurides as precursors of dilithium arylthienylcyanocuprates in a straightforward approach to phenethylamine derivatives

The ring opening reaction of N-tosyl aziridines with dilithium arylthienylcyanocuprates generated from arylbutyltellurides produced phenethylamine derivatives in good to excellent yields.

Dimerization and Isomerization Reactions of α-Lithiated Terminal Aziridines

The scope of dimerization and isomerization reactions of alpha-lithiated terminal aziridines is detailed. Regio- and stereoselective deprotonation of simple terminal aziridines with lithium 2,2,6,6-tetramethylpiperidide (LTMP) or lithium dicyclohexylamide (LiNCy2) generates trans-alpha-lithiated terminal aziridines. These latter species can then undergo dimerization or isomerization reactions depending on the nature of the N-protecting group. alpha-Lithiated terminal aziridines bearing N-alkoxycarbonyl (Boc) protection undergo N- to C-[1,2] migration to give N-H trans-aziridinylesters. In contrast, aziridines bearing N-organosulfonyl [tert-butylsulfonyl (Bus)] protection undergo rapid dimerization to give 2-ene-1,4-diamines or, if a pendant alkene is present, diastereoselective cyclopropanation to give 2-aminobicyclo[3.1.0]hexanes. All of these reactions were used as key steps in the preparation of synthetically and biologically important targets.

New ruthenium porphyrin polymeric membranes: Preparation and characterization

Abstract In this work, the ruthenium porphyrin complex Ru(4-(CF3)TPP)CO (1) (TPP = dianion of tetraphenylporphyrin) was entrapped into polymeric membranes during the phase inversion process to obtain new heterogeneous catalysts for aziridination reactions. In order to study the effect of the polymeric environment on the activity of the metallic complex, symmetric dense polymeric catalytic membranes were prepared using three different polymers: polyethersulphone (PES), polysulphone (PSf) and Hyflon AD60X. Different hydrophobicity/hydrophilicity characteristics, sorption properties and ability to retain the metallic complex characterized the catalytic polymeric membranes. On the basis of the good results compared to the other two polymers, Hyflon AD60X was selected to prepare asymmetric membranes with a skin layer on an open sublayer. The Hyflon AD60X membranes showed good catalytic activity in the aziridination reaction of α-methylstyrene by aryl azides and moreover they have been recycled without any loss in azide conversion and aziridine selectivity.

3-Benzoyl-1-[(4-methylphenyl)sulfonyl]-1a,2,3,7b-tetrahydro-1H-azireno[2,3-c]quinoline-2-carbonitrile

The title compound, C24H19N3O3S, is the result of a diastereoselective aziridination reaction performed on the corresponding Reissert adduct (1-benzoyl-1,2-dihydro­quinoline-2-carbonitrile). The aziridine ring is trans disposed to the nitrile group.