- Clarification of stereochemistry aspects for N-hydroxy-5-norbornene-2,3-dicarboximide derivatives and elucidation of them by experimental and theoretical investigations, including the synthesis of N, N'-bis-(5-exo-norbornene-2,3-dicarboxyimidyl) carbonate
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Ambiguities about the stereochemistry of N-hydroxy- 5-norbornene-2, 3-dicarboximide and N, N'-bis-(5- norbornene-2, 3-dicarboxyimidyl) carbonate and confusing naming of N-hydroxy-5-norbornene-2, 3- dicarboximide and its corresponding anhydride by literature and chemical sellers were addressed. This considered the stereochemistry itself as well as the description thereof. The unclear points could be elucidated by scientific deliberations and by practical and theoretical experiments. N, N'-bis-(5-exonorbornene- 2, 3-dicarboxyimidyl) carbonate was synthesised for the first time and for comparison, the exo and endo isomer of N-hydroxy-5-norbornene-2, 3-dicarboximide and N, N'-bis-(5-endo-norbornene-2, 3-dicarboxy-imidyl) carbonate were manufactured. The molecular structures of N-hydroxy-5-endo-norbornene-2, 3-dicarboximide and N, N'-bis-(5-endo-norbornene-2, 3-dicarboxyimidyl) carbonate have been investigated by X ray crystallography. The stereochemistry assignments of corresponding exo-endo isomers pairs were studied by various NMR experiments and the thermodynamical heat of formation were calculated by theoretical methods. The exo-endo isomers pairs can be differed easily by the chemical shifts of special atoms. For the 13C-NMR experiment is this salient atom the methylene bridge carbon and in the case of 1H-NMR experiment this role fulfilled by the protons which defines the exo-endo isomerism. Using theoretical concepts, we could illustrate that the exo carbonate is thermodynamically more stable than its corresponding endo isomer. For the exo and endo isomers of N-hydroxy-5-norbornene-2, 3-dicarboximide and their corresponding anhydrides, the exo isomers were just slightly favoured. These results underlined the experimental facts that the equilibration of them ends in a rate of nearly fifty-fifty.
- Maftei, Elena,Maftei, Catalin V.,Freytag, Matthias,Franz, M. Heiko,Bannenberg, Thomas,Neda, Ion
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p. 245 - 255
(2018/08/04)
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- Base catalysed lossen rearrangement of N-sulphonyloxy-2,3-norborn-5-enedicarboximide
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N-Sulphonyloxy-2,3-norborn-5-enedicarboximide 1 underwent Lossen rearrangement with some nucleophilic reagents, but it failed to undergo Beckmann rearrangement.
- Abbady,Kandeel,Youssef
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- Base-catalysed nucleophilic aromatic substitution reaction: Difference in reactivity between endo- and exo-2,3-(cyclopenten-3',5'-diyl)-N-(2",4"-dinitrophenoxy)succinimides with hydroxide ion and piperidine
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The reaction of 2,3-(cyclopenten-endo-3',5'-diyl)-N-(2",4"-dinitrophenoxy)succinimide (1) with hydroxide ion and piperidine in aq. acetonitrile is base-catalysed.The exo-isomer (2) reacts at a faster rate than the endo-isomer (1).The rate of the reaction in various acetonitrile-water media decreases with a decrease in water concentration for both hydroxide ion and piperidine in the case of endo-isomer and only in respect of hydroxide ion in the case of exo-isomer.The reaction rate with piperidine in the case of exo-isomer, however, increases with a decrease in the percentage of water.The mechanistic interpretation is given.
- Bhattacharjee, Gurudas,Singh, Ashok Kumar,Saikia, Ranjumoni,Yadav, Sudha
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p. 1214 - 1217
(2007/10/02)
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