Antagonistic metal-directed inductions in catalytic asymmetric aziridination by manganese and iron tetramethylchiroporphyrins

Simonato, Jean‐Pierre; Pécaut, Jacques; Marchon, Jean‐Claude; Scheidt, W. Robert

doi:10.1039/a901559k

Cited by 59 publications

(32 citation statements)

References 15 publications

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“…[1] Among the synthetic approaches to chiral aziridines, [2] the addition of a metal nitrene species to an alkene moiety is a versatile approach from readily available starting materials. [3] A number of metal complexes derived from Ag, [4] Co, [5] Cu, [1,6] Fe, [7] Mn, [8] Ru, [9] Rh [10] have been described to catalyze the aziridination of alkenes. [11] Azides, [3b,5] haloamines, [6g,i,7] iminoiodinanes, [3c] and hydroxylamine derivatives [6b,d,e,10a-d,f] are commonly used nitrene precursors.…”

Section: Introductionmentioning

confidence: 99%

A Mechanistic Study of the Stereochemical Outcomes of Rhodium‐Catalysed Styrene Aziridinations

et al. 2019

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The stereoselective, rhodium-catalysed aziridination of styrene derivatives with a chiral Nmesyloxycarbamate was found to be highly substrate dependent. A density functional theory (DFT) study is herein reported to elucidate the stereochemical outcome of the aziridination process. Rhodium acetate was initially used as a model catalyst, followed by computational studies conducted with Rh 2 [(S)-nttl] 4 . Both singlet and triplet rhodium nitrene species were identified as intermediates affording concomitant concerted and radical pathways. In the latter case, the radical intermediate appears to undergo a direct ring closure via a minimum energy crossing point (MECP) between the triplet and closed-shell singlet surfaces. Exceptionally for the m-Br-styrene aziridination, an alternative radical pathway with a carbon-carbon bond rotation was observed, accounting for the observed 74:26 mixture of diastereomers. The computational analysis also suggests little control of the metal nitrene conformation with Rh 2 (OAc) 4 with the chiral N-mesyloxycarbamate: two conformers were located affording two diastereomers of the aziridine and correlating our experimental results. On the other hand, only one conformer was found for the nitrene generated from the chiral Nmesyloxycarbamate and Rh 2 [(S)-nttl] 4 . The so-called "all-up" conformer of Rh 2 [(S)-nttl] 4 was not only the most stable metal nitrene species, but also afforded the lowest energy transition state. The calculated dr for p-Br-styrene aziridination agrees with the observed experimental result. The combination of experimental and computational results offers a detailed mechanistic picture, providing insights for further catalyst development to enhance reactivity and selectivity.

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Section: Introductionmentioning

confidence: 99%

A Mechanistic Study of the Stereochemical Outcomes of Rhodium‐Catalysed Styrene Aziridinations

et al. 2019

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“…The lower yields were obtained for alcohol esters of biocartol. Tetramethylchiroporphyrin 2a [8] (also called H 2 TMCP) and its metal complexes were needed in large amounts to screen their potential in enantiocontrol, [6,[9][10][11][12] so its yield was optimized to 20% using a 10 -3  concentration of reactants and a longer reaction time for porphyrinogen formation. Chiroporphyrin 2l was obtained in a surprisingly excellent yield (60%), which has been accounted for by the presence of complementary intramolecular hydrogen-bonding interactions between N-acylurea substituents which direct the cyclisation of the tetrapyrrolic intermediate.…”

Section: Syntheses Of Chiroporphyrins 2a-lmentioning

confidence: 99%

“…[8] We describe here the preparation and characterization of a series of D 2 -symmetric analogs, or chiroporphyrins, derived from various other esters and amides of biocartol, and from an urea derivative. Metal complexes of these chiroporphyrins have been shown to be useful as catalysts in enantioselective epoxidation and aziridination, [6,9] as hosts in chiral recognition of alcohols and β-amino alcohols, [10,11] and as chiral NMR shift reagent for amines. [12] Results and Discussion…”

Section: Introductionmentioning

confidence: 99%

D2-Symmetric Chiroporphyrins Derived from (1R)-cis-Hemicaronaldehydic Acid: Preparation and Spectral Characterization

et al. 2000

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Esters, N,N‐disubstituted amides, and a N‐acylurea derived from the enantiopure industrial intermediate (1R)‐cis‐hemicaronaldehydic acid (or biocartol) are convenient synthons for the preparation of a series of chiroporphyrins by condensation with pyrrole. These chiral meso‐tetracyclopropylporphyrins are obtained exclusively as the D2‐symmetric α,β,α,β atropisomer, generally in low to moderate yields (2‐20%), and in the urea case in excellent yield (60%). Hydrolysis of the urea substituents affords a chiroporphyrin with mono‐N‐substituted amide groups. 1H‐NMR spectroscopy indicates that the ester, amide, and urea stereogenic groups sit on the porphyrin close to the metal binding site and restrict substrate or ligand access along a C2‐symmetric groove. This structural feature of chiroporphyrins and of their metal complexes is of high potential interest in asymmetric catalysis and chiral recognition.

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“…PhI=NR compounds leading N-substituted aziridines [27], several papers were published up to 2006 [28][29][30][31][32]. As stated above, the catalytic sustainability of iron complexes is currently pushing the scientific community to devote more attention to the study of the catalytic properties of these species.…”

Section: 1mentioning

confidence: 99%

Aziridination of alkenes promoted by iron or ruthenium complexes

Damiano

Intrieri

Gallo

2018

Inorganica Chimica Acta

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Molecules containing an aziridine functional group are a versatile class of organic synthons due to the presence of a strained three member, which can be easily involved in ring-opening reactions and the aziridine functionality often show interesting pharmaceutical and/or biological behaviours. For these reasons, the scientific community is constantl y interested in developing efficient procedures to introduce an aziridine moiety into organic skeletons and the one-pot reaction of an alkene double bond with a nitrene [NR] source is a powerful synthetic strategy.Herein we describe the catalytic activity of iron or ruthenium complexes in promoting the reaction stated above by stressing the potential and limits of each synthetic protocol.

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Antagonistic metal-directed inductions in catalytic asymmetric aziridination by manganese and iron tetramethylchiroporphyrins

Cited by 59 publications

References 15 publications

A Mechanistic Study of the Stereochemical Outcomes of Rhodium‐Catalysed Styrene Aziridinations

A Mechanistic Study of the Stereochemical Outcomes of Rhodium‐Catalysed Styrene Aziridinations

D2-Symmetric Chiroporphyrins Derived from (1R)-cis-Hemicaronaldehydic Acid: Preparation and Spectral Characterization

Aziridination of alkenes promoted by iron or ruthenium complexes

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