Formation Of Aziridines Research Articles

Catalytic enantioselective formation of aziridines from α-imino esters

A new catalytic enantioselective aziridination reaction of α-imino esters with diazo compounds catalyzed by chiral Lewis acid complexes is presented. A series of N-substituted α-imino esters has been tested as substrates for the aziridination reaction using trimethylsilyldiazomethane as the carbenoid fragment donor catalyzed by various chiral complexes. Both chiral BINAP and bisoxazoline† ligands, in combination with copper(I) salts in particular can catalyze the aziridination reaction leading to the cis-aziridine with up to 72% ee applying BINAP–copper(I) complexes as the catalyst, while the bisoxazoline–copper(I) catalysts give an aziridination reaction with lower diastereoselectivity, however, the trans-aziridine was formed in 69% ee. The influence of diazo compounds, Lewis acids, chiral ligands, solvents and counterion on the reaction course has been investigated and a mechanism for the reaction is discussed in which the α-imino ester coordinates to the chiral catalyst. For trimethylsilyldiazomethane, nucleophilic attack on the coordinated α-imino ester probably takes place in the case of copper(I) as the Lewis acid, while for ethyl diazoacetate the reaction course is dependent on the Lewis acid; for silver(I) a nucleophilic attack is probably also operating, while a metal–carbene intermediate is involved when copper(I) is used.

ChemInform Abstract: Catalytic Formation of Aziridines from Imines. Characterization of an Intermediate in SnCl4‐Catalyzed Aziridination and Mechanistic Considerations.

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Catalytic formation of aziridines from imines. Characterisation of an intermediate in SnCl4-catalysed aziridination and mechanistic considerations

The tin(IV) catalysed aziridination of imines using ethyl diazoacetate as the carbene fragment donor has been investigated from a synthetic and mechanistic point of view. For imines substituted with aromatic substituents, an intermediate in the aziridination reaction has been isolated and characterised by X-ray diffraction. This intermediate is an octahedral complex with a trans coordination of two imines and in which the imines have isomerised from trans to cis by the reaction with/coordination to tin(IV). Tin(IV) is a very effective catalyst for the aziridination of various imines giving cis-aziridines as the major product. The aziridination can proceed with a very low catalyst load as 0.05 mol% of SnCl4 is sufficient to achieve a high conversion. For the formation of aziridines a linear plot of the experimental data is obtained by means of the Hammett equation for a series of competition experiments. Based on the results the mechanism for the aziridination is discussed in terms of a Lewis acid activation of the imine for a nucleophilic attack of ethyl diazoacetate.

Formation of Scalemic Aziridines via the Nucleophilic Opening of Aziridines.

ADVERTISEMENT RETURN TO ISSUEPREVNoteFormation of Scalemic Aziridines via the Nucleophilic Opening of AziridinesStephen C. Bergmeier and Punit P. SethView Author Information Division of Medicinal Chemistry, College of Pharmacy, The Ohio State University, Columbus, Ohio 43210 Cite this: J. Org. Chem. 1997, 62, 8, 2671–2674Publication Date (Web):April 18, 1997Publication History Received10 December 1996Published online18 April 1997Published inissue 1 April 1997https://doi.org/10.1021/jo962307fCopyright © 1997 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views940Altmetric-Citations34LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit Read OnlinePDF (218 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information SUBJECTS:Aziridines,Organic compounds,Organometallic reactions,Reagents,Ring opening reactions Get e-Alerts

Metal-catalysed reactions of imines with ethyl diazoacetate leading to aziridines

K. G. Rasmussen and K. Anker Jørgensen, J. Chem. Soc., Perkin Trans. 1, 1997, 1287 DOI: 10.1039/A608098G

ChemInform Abstract: Catalytic Formation of Aziridines from Imines and Diazoacetate.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 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.

Catalytic formation of aziridines from imines and diazoacetate

A catalytic method for the preparation of aziridines from imines and diazoacetate is developed using copper complexes as catalyst; the synthetic, diastereo- and enantio-selective scope of the reaction are presented.

(2H‐Azirin‐2‐yl)methyl]phosphonate: Darstellung aus allylischen α‐ und γ‐Hydroxyphosphonaten und Anwendung zur diastereoselektiven Synthese von substituirten [(Aziridin‐2‐yl)methyl]phosphonsäureestern

[(2H‐Azirin‐2‐yl)methyl]phosphonates: Synthesis from Allylic α‐ and γ‐Hydroxyphosphonates and Application to Diastereoselective Formation of Substituted [(Aziriden‐2‐yl)methyl]phosphonatesVarious substituted (3‐azido‐1‐alkenyl)phosphonates 3 (R3 = alkyl) or their equilibrium mixtures with the regioisomeric α‐azidophosphonates 4 (R3 = Ph) have been synthesized from allylic α‐ or γ‐hydroxyphosphonates 2 or 1 by Mitsunobu reaction with TPP/DEAD/HN3, and converted into the new [(2H‐azirin‐2yl)methyl]phosphonates 6 upon heating in toluene with DBU catalysis. The transformation 3/4→6 proceeds via base‐catalyzed rearrangement to the (3‐azido‐2‐alkenyl)‐phosphonates 5 and subsequent thermolysis. Reduction of the 2H‐azirines 6 with NaBH4 in methanol at 5°C results in the predominant formation of the disubstituted aziridines cis‐7. Addition of trimethylsilyl cyanide to compounds 6 yields stereoselectively the highly functionalized aziridines trans‐8, while NaOCH3‐catalyzed addition of dimethyl phosphite proceeds with even higher selectivity to yield the bisphosphonates trans‐9 with excellent yields.

ChemInform Abstract: Reductive Transformations of 6H‐1,2‐Oxazines with Hydride Reagents: Formation of Aziridines and 3‐Hydroxyalkylated 1,2‐Oxazines.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 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.

Photochemie von Acylaziden. VIII [1]. Reagieren Acylnitrene wie 1,3-Dipole??

Photochemistry of Acylazides. VIII. Do Acylnitrenes React like 1,3-Dipoles? The formation of three- ore five-membered heterocyclic rings by the reaction of acylnitrenes with olefins depends on the electron density at the double bond. The generally expected formation of aziridines by a cheletropic reaction was observed by photolysis of aroylazides 1 in the presence of 2,5-dihydrofuran 2. But with enolethers 3 and 4 oxazolines were directly formed. This [3 + 2] cycloaddition is regiospecific. The cycloaddition is modestly stereoselective by steric hindrance within the cyclic enolether 3b. Very small de-values were found with chiral substituents in the acylazide 13. The azide decomposition was also achieved by photoinduced electron transfer. The same cycloaddition products as obtained by direct photolysis of the azides were obtained via radical anions of the acylazide. Using Michler's ketone as electron donor in the triplet state the formation of isocyanate which diminishes the yield of cycloadducts can be avoided.

Reductive Transformations of 6H‐1,2‐Oxazines with Hydride Reagents: Formation of Aziridines and 3‐Hydroxyalkylated 1,2‐oxazines

Abstract6H‐1,2‐Oxazines 1 and 3 are converted into aziridines 2 and 4, respectively, by reduction with LiAlH4. Reduction of 1,2‐oxazine 5 lacking the 6‐alkoxy substituent leads to phenyl ketone 6, 6‐Alkoxy‐substituted 1,2‐oxazine‐3‐carboxylates 7, 9, and 11 are reduced with NaBH4 to give the corresponding 3‐hydroxymethylated compounds 8, 10, and 12 in good yields.

An investigation of the mitsunobu reaction in the preparation of peptide oxazolines, thiazolines, and aziridines

The diisopropyl azodicarboxylate-triphenylphosphine mediated cyclization of serine and allo-threonine derivatives provides peptide oxazolines, whereas cyclization of threonine containing substrates leads to N-acyl aziridines. In the thiopeptide series, only thiazolines are obtained. The presence of a moderately strong base is necessary for the formation of aziridines from threonine peptides.

Conversion of aziridine‐2‐carboxylic esters into 2H‐azirine‐2‐carboxylic esters

AbstractAziridine‐2‐carboxylic esters 1 were converted into 2H‐azirine‐2‐carboxylic esters 4 in two steps. Treatment of 1 with tert‐butyl hypochlorite in ether gave smooth N‐chlorination. Reaction of N‐chloroaziridines 2 with 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) or 1,4‐diazabicyclo[2.2.2]‐octane (DABCO) gave 2H‐azirine‐2‐carboxylic esters 4 in moderate yields, with concomitant formation of aziridines 1. Aziridines 1 could readily be N‐brominated with N‐bromosuccinimide. Treatment of N‐bromoaziridines 3 with base, however, did not lead to azirine formation. N‐Halogenated aziridines 2 and 3 exist as mixtures of invertomers, which slowly interconvert in solution.

ChemInform Abstract: Reactions of Aryl Azides with Alkenes in the Presence of Aluminum Trichloride. Formation of Novel Aziridines Fused to Seven‐ and Eight‐Membered Rings.

AbstractThe formation of the anilines (III), (IV), the 8‐azabicyclo(5.1.0)octanes and 9‐azabicyclo(6.1.0)nonanes ((VI), 10 examples) as well as that of the different products (VIII) or (X) and (XI) from the cis‐ (VII) or trans‐isohexene (IX), respectively, is explained by a mechanism via an azide‐AlCl3 complex, which after addition to the alkene forms an aziridinium‐AlCl3 complex.

Reactions of aryl azides with alkenes in the presence of aluminium trichloride. Formation of novel aziridines fused to seven- and eight-membered rings

Reactions of aryl azides (1) with cyclohexene gave 3-(arylamino)cyclohexenes (2) and trans-1-chloro-2-(arylamino)cyclohexanes (3), whereas that of (1) with cycloheptene or cis-cyclo-octene afforded novel aziridines, 8-aryl-8-azabicyclo[5.1.0]octanes(4), or 9-aryl-9- azabicyclo[6.1.0]nonanes (5), respectively. The reaction of phenyl azide (1a) with cis-4-methylpent-2-ene yielded 3-anilino-2-chloro-4-methylpentane (10), but that with the trans-alkene gave 4-anilino-2-methylpent-2-ene (7) and 3-anilino-4-methylpent-1-ene (8). The similar reaction of (1) with 3-trimethylsilylcyclohexene or 3-trimethylsilyl-cis-cyclo-octene produced only (2) or 3-(arylamino)-cis-cyclo-octenes (2′). The formation of the aziridines or the ring-opened products was explained by a mechanism via an aziridinium–AlCl3 complex formed from an azide–AlCl3 complex.

Cyclisation of azidoformates, formation of aziridines

Thermolysis of azidoformate (1) in refluxing 1,1,2,2-tetrachloroethane gave aziridine (2), while the same azide decomposed in toluene gave the phenoxy carbonyl azepine (6).

ChemInform Abstract: Aziridination of Cyclohex‐2‐en‐1‐ol and Geraniol: Comparison with Epoxidation.

AbstractTreatment of the cyclohexenol (II) or its derivatives (V) with the N‐aminoquinazolones (I) results in the formation of the bicyclic aziridines (III) and (IV) or (VI).

Thermal fragmentation of 2-azidobenzo[b]thiophene in the presence of alkenes: a new synthetic route to 1-(2-benzo[b]thienyl)aziridines and/or thiochroman-4-carbonitriles

Mild thermal fragmentation of 2-azidobenzo[b]thiophene in the presence of olefins results in the formation of 1-(2-benzo[b]thienyl)aziridines and/or 4-cyanothiochromans in fairly good yields. The formation of aziridines, at the expense of thiochromans, is favoured by electron-poor olefins and by a decrease in the reaction temperature. Evidence is presented in favour of a singlet nitrene intermediate which adds to the olefin double bonds or undergoes a ring-opening reaction to give an ortho-quinoidal enethione which is trapped by the alkene present. These findings provide the first example of ready ring-opening by a 2-nitreno substituted thiophene.

Zum Mechanismus der Aziridinsynthese aus 2‐Azidoalkoholen und Triphenylphosphin

On the Mechanism of the Aziridine Synthesis from 2‐Azido‐alcohols and TriphenylphosphineThe reaction of selected 2‐azido‐alcohols, their pivalates, and methanesulfonates with triphenylphosphine was investigated. It is shown that the formation of aziridines from 2‐azido‐alcohols proceeds via 1,3,2λ5oxazaphospholidines. Furthermore, the first synthesis of the unsubstituted acenaphtene‐1,2‐imine is described.

Umsetzung von 2‐Azidoalkoholen mit Trialkylphosphiten Bildung von Aziridinen und Amidophosphorsäureesten via Imidophosphorsäureester und 1,3,2λ5‐Oxazaphospholidine

Reaction of 2‐Azidoalcohols with Trialkylphosphites. Formation of Aziridines and Amidophosphates via Imidophosphates and 1,3,2λ5‐OxazaphospholidinesThe 2‐azidoalcohols 1 and 2 react with trialkyl phosphites to trialkyl (2‐hydroxy‐alkyl)imidophosphates 10, 14, and 15 respectively, whereas the 2‐azidoalcohols 3‐7 yield the 2,2,2‐trialkoxy‐1,3,2λ5‐oxazaphospholidines 16–22 under the same reaction conditions (Scheme 2). The dialkyl (2‐hydroxyalkyl)amidophosphates 23, 25, and 27–34 are obtained by the reaction of 10, and 14–22 with water (Scheme 3 and 4). By reaction with alcohols, however, both the imidophosphates 10, 14 and 15 and the 1,3,2λ5‐oxazaphospholidines 16–22 are transformed to aziridines 24, 26, and 35–38 (Scheme 5). The reactions of the imidophosphates seem to proceed via 1,3,2λ5‐oxazaphospholidines.