Cage compounds IV. 1H and 13C NMR study of 3,6‐epoxypentacyclo‐[6.2.2.02,7.04,10.05,9]dodecane and 3,6‐epoxypentacyclo‐[6.2.1.02,7.04,10.05,9]undecane

Dekker, Theodor G.; Pachler, K.G.R.; Wessels, Philippus L.; Dekker, Johannes; Fourie, L.

doi:10.1002/mrc.1270111010

Cited by 10 publications

(5 citation statements)

References 13 publications

(8 reference statements)

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“…The chemical shifts were referenced to the solvent peak [2.50 ppm for CD 3 6; number of time-incremented spectra, 256 for all spectra; relaxation delay, 2.5 s (NOESY) for 3-6; 1.5 s (HSQC and HMBC) for 3-5 and 1.5 s (COSY) for 5 and 1.0 s (COSY) for 3 and 6; spectra acquired in phase-sensitive mode, 3-6 (NOESY and HSQC); spectra acquired in absolute value mode, 3-6 (COSY and HMBC); gradients used for 3-6 (NOESY, HSQC and HMBC).…”

Section: Methodsmentioning

confidence: 99%

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Complete NMR elucidation of a novel trishomocubane hydantoin and its mono‐ and bis‐t‐Boc protected derivatives

Fourie¹,

Govender²,

Hariprakasha³

et al. 2004

Magnetic Reson in Chemistry

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The syntheses of a novel trishomocubane hydantoin and its mono- and bis-protected t-Boc derivatives are described. The less nucleophilic N-3' nitrogen of the hydantoin ring is protected first when treated with di-tert-butyl dicarbonate (t-Boc anhydride), possibly owing to steric hindrance by the bulky trishomocubane cage skeleton. More basic conditions were required to form the bis-protected t-Boc hydantoin with the same reagent. The structures of these novel compounds were elucidated with 2D NMR techniques. The proton spectrum of the trishomocubane skeleton is complex owing to major overlap of proton signals. A high-level DFT calculation was used to determine some of the crucial interatomic positions, which assisted with the elucidation of the structures. The assignment of proton and carbon signals of the three structures is described and it differs significantly from each other and also from the trishomocubanol precursor. The bis-Boc hydantoin is required for a more facile hydrolysis to the corresponding trishomocubane amino acid at room temperature.

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Section: Methodsmentioning

confidence: 99%

“…2) was achieved 15 via a Bucherer-Bergs 16 conversion of trishomocubanone (2) 11, 14,17,18 to its corresponding hydantoin (3). Base hydrolysis should yield the corresponding trishomocubane amino acid (4).…”

Section: Introductionmentioning

confidence: 99%

Complete NMR elucidation of a novel trishomocubane hydantoin and its mono‐ and bis‐t‐Boc protected derivatives

Fourie¹,

Govender²,

Hariprakasha³

et al. 2004

Magnetic Reson in Chemistry

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“…Evaporation of the organic solvent resulted in the crude product, which was purified via silica gel column chromatography (dichloromethane). The product (6, 13 …”

Section: Synthesis Of the Hydantoin Diastereomermentioning

confidence: 99%

“…Although NMR elucidation of the pentacyclo-undecane cage system is well studied 1 School of Chemistry, University of KwaZulu-Natal, Durban 4001, South Africa. 2 To whom all corespondence should be addressed; e-mail: kruger@ ukzn.ac.za [2,3,5,[13][14][15][16][17], similar studies on the intrinsically chiral [8] trishomocubane systems [6,7,[18][19][20] are somehow neglected. Various authors [16,[21][22][23] have commented on the difficulty of NMR elucidation of these cage compounds.…”

Section: Introductionmentioning

confidence: 99%

Complete NMR Elucidation of Two N-Protected Trishomocubane Hydantoins and the Ethyl Ester of the Corresponding Amino Acid

2005

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In an attempt to resolve a racemic mixture of a trishomocubane hydantoin, the synthesis of a pair of novel diastereomers was obtained by protecting the racemic hydantoin with chlorocarbonic acid-(−)(R)-sec-butyl ester. An achiral i-propyl ester was first used to establish the procedure. The NMR elucidation of both the chiral and achiral N-protected hydantoins is described. Some proton and carbon NMR shifts on the cage are reversed when relative small changes on the protection group are introduced. The chiral centre on the protective group induced splitting of some carbon signals in the 13 C spectrum on the cage skeleton, but effective separation of the diastereomers could not be obtained. In a further attempt to demonstrate the potential use of the trishomocubane amino acid in peptide synthesis, the ethyl ester of the cage amino acid was synthesised. The structures of the amino acid derivatives were elucidated with 2D NMR techniques and the assignment of the NMR data is presented.

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“…Although NMR elucidation of the pentacyclo-undecane cage system is well studied [9,[22][23][24][25][26][27][28], the elucidation of these cage systems remains very complex due to major overlap of proton signals and some carbon signals of the cage skeleton. The previous reported [9] NMR elucidation of the PCU hydantoin (5) was useful and the same numbering system was also adopted.…”

Section: Discussion Of the Resultsmentioning

confidence: 99%

Regioselective protection of hydantoins – essential for hydantoin based anti-epileptic drugs

Kruger

Mdluli

2006

Struct Chem

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The synthesis and NMR elucidation of six novel mono-and bis-Boc protected hydantoins are reported. The hydantoins 5-methylhydantoin, 5,5-dimethylhydantoin and a pentacycloundecane hydantoin exhibit an increase in substitution and steric hindrance at C-5. Kinetic and reagent controlled monoprotection of the smaller hydantoins achieve regioselective protection at N-1 while the bulky cage hydantoin is protected at N-3 . Hydantoin based anti-epileptic drugs such as 5,5-diphenylhydantoin require regioselective substitution at N-3 for enhanced pharmaceutical activity. The study enhances our understanding of the activity of the nitrogen atoms on hydantoin rings.

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Cage compounds IV. ¹H and ¹³C NMR study of 3,6‐epoxypentacyclo‐[6.2.2.0^2,7.0^4,10.0^5,9]dodecane and 3,6‐epoxypentacyclo‐[6.2.1.0^2,7.0^4,10.0^5,9]undecane

Cited by 10 publications

References 13 publications

Complete NMR elucidation of a novel trishomocubane hydantoin and its mono‐ and bis‐t‐Boc protected derivatives

Complete NMR elucidation of a novel trishomocubane hydantoin and its mono‐ and bis‐t‐Boc protected derivatives

Complete NMR Elucidation of Two N-Protected Trishomocubane Hydantoins and the Ethyl Ester of the Corresponding Amino Acid

Regioselective protection of hydantoins – essential for hydantoin based anti-epileptic drugs

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