Stereocontrolled Aziridination of Imines via a Sulfonium Ylide Route and a Mechanistic Study

Yang, Xiaofang; Zhang, Mingjie; Hou, Xue‐Long; Dai, Li‐Xin

doi:10.1021/jo0257389

Cited by 60 publications

(33 citation statements)

References 49 publications

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“…The results obtained are in contrast to many reports in which epoxides are the final products [3a] [11]. Earlier, a similar difference was observed, when the reaction was performed between N-tosyl aldimine and (2-ethoxy-2-oxoethyl)(dimethyl)sulfonium bromide (2A) by using NAP-MgO, since b-amino asulfanyl ester [10d] was obtained instead of the predicted aziridine [12].…”

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confidence: 88%

Synthesis of β‐Hydroxy α‐Sulfanyl Esters by Using Nanocrystalline Magnesium Oxide

Mahendar

Sarma

Raghavaiah

et al. 2011

Helvetica Chimica Acta

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Aldol-type reaction between electron deficient aldehydes and sulfonium salts to afford the corresponding b-hydroxy a-sulfanyl esters in moderate-to-good yields by using nanocrystalline MgO is described. The sulfanyl group is a useful group for further transformations in organic synthesis. Low R fvalue isomer is anti-configured as revealed by X-ray diffraction study and consistent with the assignment of 1 H-NMR spectrum.Introduction.-b-Hydroxy a-sulfanyl esters have found widespread use in organic synthesis, particularily for the synthesis of natural products and pharmaceuticals [1]. The sulfanyl functionality is expected to act as a useful group for further transformations in the synthesis of a large number of target molecules [2].Consequently, numerous methods have been reported for the synthesis of bhydroxy a-sulfanyl esters. Aldol condensation of a-alkylsulfanylacetates with aldehydes catalyzed by LDA, diazaborolidine, TiCl 4 /Et 3 N have been presented [3]. Ketene silyl acetals derived from 2-(alkylsulfanyl)propanoates were reacted with aldehydes in the presence of Sn(OTf) 2 , MgBr 2 , oxazaborolidinone, to afford b-hydroxy a-methyl a-(methylsulfanyl) esters in good yields [4]. The nucleophilic ring opening of the cyclic carbonates of threo-2,3-dihydroxy esters with thiols [5] and reduction of b-keto asulfenyl esters using Ca(BH 4 ) 2 or Bakers yeast as catalyst [6] produce also b-hydroxy a-sulfanyl esters. Alternatively, stereoselective conjugate addition of lithium or sodium thiolate to the BaylisÀHillman adducts [7], and a combination of a,b-unsaturated ester, aldehyde, lithium or magnesium thiolate leads, in a one-pot Michael/aldol tandem reaction [8], to a-[(1-alkylsulfanyl)alkyl] b-hydroxy esters in good yields. However, to the best of our knowledge, there is no report on synthesis of b-hydroxy a-sulfanyl esters by using heterogeneous catalysts.Nanocrystalline metal oxides found excellent applications as active adsorbents for gases, for destruction of hazardous chemicals [9], and as catalysts for various organic transformations [10]. These high reactivities are due to high surface areas combined with unusually reactive morphologies. In continuation of our work on the application of nanomaterials in synthetic methodologies, here, we report an effective aldol-type

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confidence: 88%

Synthesis of β‐Hydroxy α‐Sulfanyl Esters by Using Nanocrystalline Magnesium Oxide

Mahendar

Sarma

Raghavaiah

et al. 2011

Helvetica Chimica Acta

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“…Surprisingly, these results are in contrast to many reports in which aziridine, aziridinyl carboxamide or b-amino alkenes are the final products [98][99][100]. In order to understand the relationship between structure and reactivity (please refer Fig.…”

Section: Mannich-type Reactionscontrasting

confidence: 61%

“…NAP-MgO catalyzed Mannich-type reaction between N-sulfonyl aldimines 1 and ester sulfonium salts 2A-D[99] …”

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confidence: 99%

Recent Developments on Catalytic Applications of Nano-Crystalline Magnesium Oxide

Chintareddy

Kantam

2011

Catal Surv Asia

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Nanocrystalline metal oxides, MgO, CuO, ZnO, TiO 2 as catalysts or catalyst supports have been received much attention in the recent years, especially nanocrystalline magnesium oxide (NAP-MgO) has been used as a recyclable catalyst for Wittig, WadsworthEmmons, aza-Michael, Baylis-Hillman, Strecker, Aldol, Claisen-Schmidt condensation and other useful organic reactions. In general, it is reported that nanocrystalline magnesium oxide shows better activity in many organic reactions. These high reactivities are due to high surface areas combined with unusually reactive morphologies. The nanomaterials were also explored as supports to make supported metal catalysts for the organic reactions. The higher activity of these catalysts was studied partly to understand the mechanism of the reaction, the putative reaction pathways were preliminarily presented with the help of spectroscopic support, XPS, silicon, and phosphorus NMR spectroscopy. The catalysts are recovered and reused for several cycles. These catalytic systems are expected to contribute to the development of benign chemical processes.

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“…[9] Vinylaziridines were also prepared from vinyl epoxides by ring opening with azides (path e), from 1,2-amino halides (path c), [10] and by conjugate addition. [11] The aforementioned nitrene addition to dienes (path d) [4,5] have been described, but they can be yet considered far from successful in terms of regio-and stereoselectivity.…”

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confidence: 99%

Efficient Silver‐Catalyzed Regio‐ and Stereospecific Aziridination of Dienes

et al. 2010

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The synthesis of aziridine derivatives through metal-mediated nitrene addition reactions to olefins [Eq. (1)] has been extensively developed in the last decades; quantitative conversions as well as complete enantioselection have been already described. [1,2] However, in spite of the large number of reports related to the alkene aziridination reaction by this method and the synthetic interest of vinylaziridines, [3] only few have dealt with conjugated dienes as the substrate. Copper-, [4] manganese-, and ruthenium-based [5] catalysts have provided good yields of vinylaziridines formed by the exclusive aziridination of one C = C bond of the diene, although with the following limitations: 1) only symmetric dienes were employed and 2) selectivity, intended as cis/trans (or trans/cis) ratio, was low. These two drawbacks strongly prevent the synthetic application of this method.In fact, vinylaziridines are commonly synthesized by stoichiometric procedures based on nucleophilic intramolecular substitution. Thus, the Darzens-type reaction (Scheme 1, path a) is one of the oldest and most flexible methods for preparation of functional aziridine derivatives including vinylaziridines.

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Stereocontrolled Aziridination of Imines via a Sulfonium Ylide Route and a Mechanistic Study

Cited by 60 publications

References 49 publications

Synthesis of β‐Hydroxy α‐Sulfanyl Esters by Using Nanocrystalline Magnesium Oxide

Synthesis of β‐Hydroxy α‐Sulfanyl Esters by Using Nanocrystalline Magnesium Oxide

Recent Developments on Catalytic Applications of Nano-Crystalline Magnesium Oxide

Efficient Silver‐Catalyzed Regio‐ and Stereospecific Aziridination of Dienes

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