Formation Of Aziridines Research Articles

Catalytic Asymmetric Aziridination with Catalysts Derived from VAPOL and VANOL

This Account describes the discovery and development of the catalytic asymmetric aziridination reaction (AZ reaction) that has been the subject of efforts in our laboratory over the last 12 years. The optimized catalyst system involves catalysts generated from either the VAPOL or VANOL ligand and triphenyl borate. These catalysts are effective for formation of aziridines from the reac­tion of imines that bear a N-benzhydryl substituent with stabilized diazo compounds including the commercially available ethyl diazoacetate (EDA). The reaction is general for N-benzhydryl im­ines prepared from electron-rich and electron-poor aromatic aldehydes, as well as from primary, secondary and tertiary aliphatic aldehydes. This reaction is highly enantioselective and diastereo­selective giving cis-3-substituted aziridine-2-carboxylates in excellent yields. This Account presents the scope of the AZ reaction as defined by the work that has been done in our laboratory up to the present time, as well as applications of the resulting aziridines that have been demonstrated to date.

Carbohydrate-Based Spiro-1,3-oxazolidine-2-thiones: Stereoselective Approaches Using Aziridines and Epoxides

D-glucose and D-fructose have been used as starting materials to prepare spiro-1,3-oxazolidine-2-thiones anchored on the third position of both carbohydrates. Following different approaches and depending on the carbohydrate template explored, stereoselective reactions have been developed via the formation of epoxides or aziridines.

Expeditious and Practical Synthesis of Various Substituted Taurines from Amino Alcohols

Various substituted taurines have been synthesized expeditiously and practically in satisfactory to good yields directly from amino alcohols using a two-step, one-pot procedure, in which the amino alcohols undergo sulfuric acid esterification and subsequent sodium sulfite substitution. Treatment of amino-substituted secondary alcohols using the same procedure gave 2-substituted or 1,2-di­substituted taurines, indicating the formation of aziridines as intermediates during the substitution step. This method is one of the most efficient routes for preparing structurally diverse 2-substituted and 1,2- and 2,2-disubstituted taurines.

Reactions of Nitroso Hetero‐Diels—Alder Cycloadducts with Azides: Stereoselective Formation of Triazolines and Aziridines.

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Reactions of Nitroso Hetero-Diels−Alder Cycloadducts with Azides: Stereoselective Formation of Triazolines and Aziridines

The addition of azides to acylnitroso hetero-Diels-Alder cycloadducts derived from cyclopentadiene affords exo-triazolines in excellent yield. The reaction is greatly affected by the level of alkene strain, while sterically demanding azides do not hinder the reaction. Conversion of the triazolines to aziridines is also described.

Synthesis of Asymmetric N‐Arylaziridine Derivatives Using a New Chiral Phase‐Transfer Catalyst.

Substituted N-arylaziridine derivatives were synthesized in an enantioselective manner from N-acyl-N-arylhydroxylamine and electron deficient olefins using chiral phase-transfer catalysts (CPTCs) derived from cinchona alkaloids. The structures of the CPTCs were ascertained through various spectral techniques such as FT-IR, 1 H NMR, 1 3 C NMR, and mass spectroscopy, as well as elemental analyses. The efficiency and chiral behavior of a range of CPTCs were studied with respect to both yield and ee. The chemical yields were in the range of 24-92% and ee was 29-95%. It was observed that the S-enantiomers were more predominant than the R-enantiomers with cinchonidine as catalyst; whereas the /?-enantiomers were more predominant in the case of cinchonine based CPTC. We propose here a suitable mechanism for the formation of chiral aziridines as well as optimized procedures for a range of N-arylaziridine derivatives.

The First Example of Catalytic Aziridination Mediated by Arsonium Ylides: Preparation of trans‐Pentafluorophenyl‐Containing Aziridines.

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Synthesis of AsymmetricN-Arylaziridine Derivatives Using a New Chiral Phase-Transfer Catalyst

Substituted N-arylaziridine derivatives were synthesized in an enantioselective manner from N-acyl-N-arylhydroxylamine and electron deficient olefins using chiral phase-transfer catalysts (CPTCs) derived from cinchona alkaloids. The structures of the CPTCs were ascertained through various spectral techniques such as FT-IR, 1H NMR, 13C NMR, and mass spectroscopy, as well as elemental analyses. The efficiency and chiral behavior of a range of CPTCs were studied with respect to both yield and ee. The chemical yields were in the range of 24-92% and ee was 29-95%. It was observed that the S-enantiomers were more predominant than the R-enantiomers with cinchonidine as catalyst; whereas the R-enantio­mers were more predominant in the case of cinchonine based CPTC. We propose here a suitable mechanism for the formation of chiral aziridines as well as optimized procedures for a range of N-arylaziridine derivatives.

The First Example of Catalytic Aziridination Mediated by Arsonium Ylides: Preparation oftrans-Pentafluorophenyl-Containing Aziridines

Triphenylarsine catalyzes the formation of aziridines from tosyl imines and aromatic diazo compounds in a one-pot reaction. It is the first example of catalytic aziridination mediated by arsonium ylides. It gave aziridines in excellent diastereoselectivity with pentafluorophenyl diazomethane as the substrate. This catalytic reaction is complementary with the reaction mediated by sulfur ylides.

Silica—Water Reaction Media: Its Application to the Formation and Ring Opening of Aziridines.

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Corey—Chaykovsky Reaction of Chiral Sulfinyl Imines: A Convenient Procedure for the Formation of Chiral Aziridines.

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Silica-water reaction media: its application to the formation and ring opening of aziridines.

Olefins can be converted into aziridines by using a chloramine-T/I2 system, and silica and water as the reaction medium (see picture). Moreover, the ring-opening reaction of the resulting aziridine with an azide or a cyanide ion proceeds in the same medium. Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2002/2004/z52842_s.pdf or from the author. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Silica–Water Reaction Media: Its Application to the Formation and Ring Opening of Aziridines

Aziridine aus Olefinen werden mit Chloramin-T/I2-Systemen in Wasser oder Kieselgel als Reaktionsmedium erhalten (siehe Bild). Die Ringöffnung der entstandenen Aziridine kann mit Azid- oder Cyanidionen im selben Medium durchgeführt werden.

Reagent‐Controlled Diastereoselective Aminations with a New Chiral Nosyloxycarbamate.

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Reagent-controlled diastereoselective aminations with a new chiral nosyloxycarbamate

The synthesis of a new chiral nosyloxycarbamate derived from Helmchen's auxiliary is described. Reactions performed with this aminating reagent successfully give the formation of diastereomeric allylic carbamates or diastereomeric aziridines starting from different kinds of olefins.

Corey-Chaykovsky Reaction of Chiral Sulfinyl Imines: A Convenient Procedure for the Formation of Chiral Aziridines

The reaction of dimethylsulfonium methylide with a range of aromatic, heterocyclic and aliphatic tert-butylsulfinyl imines­ is presented. Aziridines were formed in 63-84% yield and 77-95% diastereomeric excess.

4 Heterocyclic chemistry

It has been a very active year in the arena of heterocyclic chemistry. Particular highlights include a new catalytic system for the formation of aziridines with easily removable N-protecting groups (Du Bois); two examples of catalytic asymmetric Staudinger β-lactam formation, independently reported by Fu and Lectka; the use of ynamine chemistry to access γ-butyrolactones in an asymmetric fashion (Jacobsen); and an extremely versatile methodology for the synthesis of highly substituted pyridines from Bagley and co-workers.

Asymmetric synthesis of N-aryl aziridines

The reactions of a variety of N-arylhydroxamates as nitrogen transfer reagents to acryloyl derivatives of (−)-8-phenylmenthol, (−)-quinine and (−)-Oppolzer's sultam acting as Michael acceptors was studied. Poor to modest diastereoselection was observed in the formation of aziridines. The absolute structure of one of the pure diastereomers secured from Oppolzer's auxiliary was established by X-ray crystallography and hence the absolute configuration of the derived methyl- N-phenylaziridine-2-carboxylate could be assigned. Whilst only poor facial selectivity was observed for chiral hydroxamic acid prepared from dehydroabietic acid, moderate to good enantioselection of aziridines could be achieved with the chiral quaternary salts based on cinchona alkaloids, especially with that of cinchonine. A model is presented to explain the origin of enantioselection and a mechanism is proposed for the aziridination reaction.

Design and synthesis of MMP inhibitors using N-arylsulfonylaziridine hydroxamic acids as constrained scaffolds

The synthesis of cis- and trans-aziridine hydroxamic acid derivatives as MMP inhibitors is described using enantio- and diastereoselective methods for the formation of trisubstituted aziridines. Their preliminary inhibitory activity is reported and discussed in the context of modeling studies.

ChemInform Abstract: Catalytic Enantioselective Formation of Aziridines from α‐Imino Esters.

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.