Highly regioselective ring opening of epoxides and aziridines using cerium(III) chloride

Sabitha, Gowravaram; Babu, R. Satheesh; Rajkumar, M.; Reddy, C. Suresh; Yadav, J. S.

doi:10.1016/s0040-4039(01)00622-0

Cited by 104 publications

(48 citation statements)

References 28 publications

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“…The preparation of graed graphite is shown schematically in Fig. 1(c) and proceeded as follows: GO and ring-opened TGIC were placed in a DMF solution, mixed in a 150 mL threenecked round-bottomed ask, and stirred for 8 h in a water bath at 80 C. 23 The reaction solution was centrifuged, washed repeatedly with distilled water until the solution became almost neutral, and dried in a drying oven at 70 C. The nal product was stored until use.…”

Section: Preparation Of Graed Graphitementioning

confidence: 99%

Surface modification and thermal performance of a graphene oxide/novolac epoxy composite

Fang

et al. 2018

RSC Adv.

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Functionalized graphene oxide (GO) was successfully modified by grafting 1,3,5-triglycidylisocyanurate (TGIC) onto the surface of GO. The modified GO was then added to a novolac epoxy composite at various volume fractions to improve the interfacial compatibility between the filler and matrix. Samples of the modified GO/novolac epoxy composite were fabricated through the hot-pressing method.Microstructural analysis revealed that the modified GO dispersed well in the matrix and formed thermal conductive pathways across the matrix. The thermal degradation temperature of 50% weight loss of the modified GO/novolac epoxy composite was 166 C higher than that of the novolac epoxy. The data for loss factor tan d demonstrated that when the composite contained 36.8 wt% of modified GO, the glass transition temperature of the modified GO/novolac epoxy composite was 222 C, which is 90 C higher than that of the novolac epoxy. The thermal conductivity of the modified GO/novolac epoxy composite. Results indicated that the incorporation of surface-modified GO into the novolac epoxy positively affects the thermal conductivity and various properties of the modified GO/novolac epoxy composite.

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Section: Preparation Of Graed Graphitementioning

confidence: 99%

Surface modification and thermal performance of a graphene oxide/novolac epoxy composite

Fang

et al. 2018

RSC Adv.

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“…[20][21][22][23][24][25][26][27] Previous reports have shown that replacement of the hydrogen of the N-H moiety with an electron-withdrawing substituent increases the susceptibility of N-H aziridines to ring-opening or ring-enlargement reactions. [28][29][30] So, our first aim was to synthesize N-Boc-substituted ketoaziridines as a precursor for preparation of the corresponding nitrogen-containing compounds via ring opening or ring enlargement. At first, we investigated the reaction of ditert-butyl dicarbonate [(Boc) 2 O] and 2-(4-chlorobenzoyl)-3-(4-chlorophenyl)aziridine (1a) in chloroform, acetonitrile, ethanol or acetone in the presence of triethylamine.…”

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confidence: 99%

Synthesis of tert-Butyl 1,3-Diaryl-3-oxopropylcarbamates by a Regiocontrolled Reduction of Ketoaziridines

Samimi

Yamin²,

Saberi

2014

Synthesis

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A new, convenient approach for the reductive ring opening of N-H ketoaziridines is described. Treatment of N-H ketoaziridines with di-tert-butyl dicarbonate [(Boc) 2 O] in the presence of sodium iodide and nickel(II) chloride results in the corresponding tert-butyl 1,3-diaryl-3-oxopropylcarbamates by a regiocontrolled reaction. The structure of the regioisomeric product was confirmed by X-ray crystal structure analysis.

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“…Analysis of recently published data on reactions of N-sulfonylaziridines with nucleophiles [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] showed that the main factors determining the reaction direction are electronic properties of the substituent in the aziridine ring and the nature of nucleophile. Steric factor and reaction conditions also play a definite role [7].…”

mentioning

confidence: 99%

“…Steric factor and reaction conditions also play a definite role [7]. For example, 2-aryl-1-(4-methylphenylsulfonyl)aziridines react with C-, O-, S-, and Hlg-nucleophiles either exclusively or preferentially at the N-C 2 bond [8-10, [14][15][16][17], whereas the N-C 3 bond is cleaved in 2-alkyl-1-(4-methylphenylsulfonyl)aziridines [18][19][20][21]. An exception is the reaction of 1-(4-methylphenylsulfonyl)-2-phenylaziridine with benzenethiol [17], which afforded isomeric products resulting from opening of the aziridine ring at the N-C 2 and N-C 3 bonds at a ratio of 1 : 1.…”

mentioning

confidence: 99%

Formation of 2,6-diphenyl-1,4-bis(trifluoromethylsulfonyl)piperazine in the reaction of styrene with trifluoromethylsulfonylnitrene

Moskalik

Shainyan

2011

Russ J Org Chem

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The reaction of styrene with trifluoromethylsulfonylnitrene generated in the system t-BuOCl-NaI led to the formation of trifluoro-N-[2-phenyl-2-(trifluoromethylsulfonylamino)ethyl]methanesulfonamide CF 3 SO 2 NHCH(Ph)CH 2 NHSO 2 CF 3 , 2-iodo-1-phenylethanol, and heterocyclization product, 2,6-diphenyl-1,4-(trifluoromethylsulfonyl)piperazine. The latter is regioisomeric to 2,5-diphenyl-1,4-(trifluoromethylsulfonyl)-piperazine obtained previously by analogous reaction in the system t-BuOCl-NaI · 2 H 2 O.We recently studied the reaction of styrene with trifluoromethylsulfonylnitrene CF 3 SO 2 N: generated from trifluoromethanesulfonamide in the system t-BuOClNaI · 2 H 2 O and obtained 2,5-diphenyl-1,4-bis(trifluoromethylsulfonyl)piperazine (I) together with other products. The structure of compound I was determined by X-ray analysis, and a probable mechanism of its formation was proposed [1]. Unexpectedly, compound I was also obtained by dehydrobromination of N-(2-bromo-2-phenylethyl)trifluoromethanesulfonamide (II) by the action of triethylamine [2] (Scheme 1).Compound I was not the major product in the reaction of styrene with trifluoromethylsulfonylnitrene; apart from I, trifluoro-N-[2-phenyl-2-(trifluoromethylsulfonylamino)ethyl]methanesulfonamide (III) and 2-iodo-1-phenylethanol (IV) were formed [1]. With a view to obtain the corresponding aziridine [3] we modified the system t-BuOCl-NaI · 2H 2 O and used anhydrous sodium iodide. The reaction occurred in a way similar to that reported previously [1], i.e., with formation of compounds III and IV as products of opening of the aziridine ring in the primary addition product of trifluoromethylsulfonylnitrene to styrene. However, the third isolated compound (V) differed from piperazine I obtained previously. Its 1 H NMR spectrum contained signals from aromatic protons and an ABX spin pattern, but the H A signal was displaced by 0.3 ppm upfield, and the H B and H X signals were located in a weaker field (by 0.2 and 0.1 ppm, respectively) relative to the corresponding signals in the spectrum of I. In the 13 C NMR spectrum of compound V the CH carbon atom resonated in a stronger field (by 5 ppm), and the most important difference from the spectrum of I was the presence of two signals assignable to CF 3 group. Correspondingly, two different signals were observed in the 19 F NMR spectrum of V. The above data allowed us to assign compound V the structure of 2,6-diphenyl-1,4-bis(trifluoromethylsulfonyl)piperazine (Scheme 2).Apart from the presence of signals from two magnetically nonequivalent trifluoromethyl groups in the NMR spectra, the unsymmetrical structure of compound V was confirmed by the mass spectral data. The exact molecular weights of I and V coincide with each

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Highly regioselective ring opening of epoxides and aziridines using cerium(III) chloride

Cited by 104 publications

References 28 publications

Surface modification and thermal performance of a graphene oxide/novolac epoxy composite

Surface modification and thermal performance of a graphene oxide/novolac epoxy composite

Synthesis of tert-Butyl 1,3-Diaryl-3-oxopropylcarbamates by a Regiocontrolled Reduction of Ketoaziridines

Formation of 2,6-diphenyl-1,4-bis(trifluoromethylsulfonyl)piperazine in the reaction of styrene with trifluoromethylsulfonylnitrene

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