Chirale Aziridine — Herstellung und stereoselektive Transformationen

Tanner, David

doi:10.1002/ange.19941060604

Cited by 163 publications

(38 citation statements)

References 201 publications

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“…[6] The influence of the N-protecting group, imine substituent, and the sulfonium salt structure on the diastereoselectivity of the reaction was studied and found to be highly substrate dependent. The cis/trans ratios were determined by 1 H NMR spectroscopic analysis of the crude product. As expected, [3c] the best trans selectivity was obtained in the reactions with imines bearing the N-Boc substituent (trans diastereomeric excess (de) 80-100 %, Tables 1 and 2).…”

Section: Resultsmentioning

confidence: 99%

“…During the past two decades, many different methods for asymmetric aziridination have been developed. [1] Amongst them, a significant number involve imine aziridinations using a carbene, [2] or a carbene equivalent, such as sulfur ylides. The reactions of chiral sulfur ylides with imines have proven to be a very powerful method for asymmetric aziridinations.…”

Section: Introductionmentioning

confidence: 99%

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Sulfur Ylide Promoted Synthesis of N‐Protected Aziridines: A Combined Experimental and Computational Approach

Dokli¹,

Matanović²,

Hameršak³

2010

Chemistry A European J

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A range of N-protected aziridines [N-Tosyl (N-Ts), N-2-trimethylsilylethanesulfonamide (N-SES), N-tert-butoxycarbonylamido (N-Boc), and N-o-nitrobenzenesulfonamide (oNs)] were prepared in moderate to good yield and with high enantiomeric excess of both isomers starting from N-protected imines, using a sulfonium salt derived from Eliel's oxathiane. The diastereoselectivities of the reactions are influenced by the imine N-protecting group, the imine substituent, and the sulfide structure. An unusual cis selectivity was observed in the formation of N-tosyl-2-phenyl-3-tert-butylaziridine and N-o-trimethylsilylethanesulfonamide-2-phenyl-3-tert-butylaziridine, which was explained by using computational models. The analysis suggests that betaine formation in the case of N-tosyl-tert-butylaldimine aziridination using oxathiane benzyl sulfonium ylide 1' is reversible and that the selectivity is determined at the rotation step, which is unusual for semistabilized ylide aziridination. We have shown herein that the steric bulk of an imine substituent, in combination with a sterically demanding sulfonium ylide, can also affect the reversibility of the reaction. This is the first example of this sort involving aziridinations using semistabilized ylides.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Sulfur Ylide Promoted Synthesis of N‐Protected Aziridines: A Combined Experimental and Computational Approach

Dokli¹,

Matanović²,

Hameršak³

2010

Chemistry A European J

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“…The precipitate was collected and washed twice with cyclohexane to yield (6-tert-butyl-2,3,4-trimethylphenyl)methylene diacetate (774 mg, 2.6 mmol, 60 %) as a white solid. 1 N-Tosylimino(1-tert-butyl-3,4,5-trimethylbenzene)iodinane: [14] p-Toluenesulfonamide (416 mg, 2.43 mmol) and KOH (325 mg, 5.79 mmol) were dissolved in MeOH (8 mL) and cooled to 0 8C. Under stirring, 1-tertbutyl-2(diacetoxyiodo)-3,4,5-trimethylbenzene (682 mg, 2.32 mmol) was added at 10 8C.…”

Section: Methodsmentioning

confidence: 97%

“…The chemistry of three-membered ring heterocycles, especially that of the aziridines, has inspired organic chemistry for decades, [1][2][3] and the development of suitable methods for their synthesis has a long history. [4,5] Aziridines may be prepared by stoichiometric or catalytic reactions (see Scheme 1).…”

Section: Introductionmentioning

confidence: 99%

“…[6,7] The transition-metal-catalyzed route is often used due to its efficiency, and many examples have been studied in detail. [1,3,5,[8][9][10][11][12][13] Due to its high reactivity, PhINTs ([N-(p-toluenesulfonyl)imino]phenyliodinane) is generally used as the nitrene source, although others such as chloramine T have economic and ecological advantages. [4,5,8,14,15] Various reaction mechanisms have been proposed for the transition-metal-catalyzed processes, and these include stepwise pathways with radical intermediates as well as concerted reactions, and nitrene complex intermediates with the metal ions in various oxidation states (e.g., for copper: Cu I , Cu II , Cu III ) have been suggested; mechanisms that do not include any electron-transfer steps at the metal center and Lewis acid based mechanisms with non-redox-active metal ions such as Zn 2 + and Mg 2 + have also been proposed.…”

Section: Introductionmentioning

confidence: 99%

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Synthesis, Structure, and Highly Efficient Copper‐Catalyzed Aziridination with a Tetraaza‐Bispidine Ligand

Comba

Haaf

Lienke

et al. 2009

Chemistry A European J

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The distorted trigonal-bipyramidal Cu(II) complex [Cu(L(1))(NCCH(3))](2+) of the novel tetradentate bispidine-derived ligand L(1) with four tertiary amine donors (L(1)=1,5-diphenyl-3-methyl-7-(1,4,6-trimethyl-1,4-diazacycloheptane-6-yl)diazabicyclo[3.3.1]nonane-9-one) is a very efficient catalyst for the aziridination of olefins in the presence of a nitrene source. In agreement with the experimental data (in situ spectroscopy, product distribution, and its dependence on the geometry of the substrate and of the nitrene source), a theoretical analysis based on DFT calculations indicates that the active catalyst has the Cu center in its +II oxidation state, that electron transfer is not involved, and that the conversion of the olefin to an aziridine is a stepwise process involving a radical intermediate. The striking change of efficiency and reaction mechanism between classical copper-bispidine complexes and the novel L(1)-based catalyst is primarily attributed to the structural variation, enforced by the ligand architecture.

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An Easy Access to 1-Azaspiropentane-2-carboxamides – The First Derivatives of a New Type of Amino Acids

Tamm¹,

Thutewohl²,

Ricker³

et al. 1999

Eur. J. Org. Chem.

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Azaspiropentanecarboxamides 10 and 12 are formed with remarkable ease in two steps in a one‐pot operation from methyl 2‐chloro‐2‐cyclopropylideneacetate (4) by addition of a primary amine in tetrahydrofuran and subsequent treatment with sodium hydride/triethylamine in the presence of another equivalent of a primary amine or ammonia. Achievable yields of the amides 10, 12 were moderate to good (27–59%, 12–48%), while the corresponding esters 9 could only be obtained in poor yields (4–14%). The new α‐amino acid amides are surprisingly stable, and they can be incorporated into small peptides as demonstrated with the preparation of the glycine 13e and the spirocyclopro‐paneoxazoline derivative 14e.

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Chirale Aziridine — Herstellung und stereoselektive Transformationen

Cited by 163 publications

References 201 publications

Sulfur Ylide Promoted Synthesis of N‐Protected Aziridines: A Combined Experimental and Computational Approach

Sulfur Ylide Promoted Synthesis of N‐Protected Aziridines: A Combined Experimental and Computational Approach

Synthesis, Structure, and Highly Efficient Copper‐Catalyzed Aziridination with a Tetraaza‐Bispidine Ligand

An Easy Access to 1-Azaspiropentane-2-carboxamides – The First Derivatives of a New Type of Amino Acids

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