Synthesis of 4-oxahexacyclo[5.4.1.02,6.03,10.05,9.08,11]dodecane-3-carboxylic acid

Martins, Charles Ferreira; Viljoen, A. M.; Kruger, Hendrik G.; Wessels, Philippus L.

doi:10.1016/s0040-4020(01)80168-x

Cited by 13 publications

(8 citation statements)

References 4 publications

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“…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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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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“…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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“…[1,14 -16] Our group has successfully utilized these techniques in the elucidation of numerous PCU derivatives synthesized in our laboratory. [17 -24] As part of our ongoing program in this field, the NMR assignment of eight novel PCU derivatives (1)(2)(3)(4)(5)(6)(7)(8) is reported (Fig. 1).…”

Section: Introductionmentioning

confidence: 99%

Synthesis and NMR assignment of pentacycloundecane precursors of potential pharmaceutical agents

Onajole

Makatini

Gasqui

et al. 2010

Magnetic Reson in Chemistry

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The synthesis and complete NMR elucidation of eight novel pentacycloundecane (PCU) derivatives are reported. These compounds are precursors in the synthesis of PCU-based anti-tuberculosis (TB) agents and potential human immunodeficiency virus (HIV) protease inhibitors. Two-dimensional (2D) NMR techniques were used to assign the NMR spectra for these compounds. Substitution of the cage molecule at (C-8/11) further complicates the assignment, since some of the substituted alkyl chain groups overlap with the cage proton signals. The side chain heteroatoms also introduce a rare through-space deshielding effect to some of the carbon atoms of the cage skeleton. Ring strain in the rigid cage skeleton appears to induce drastic electronic changes in some parts of the cage framework. This observation is more dramatic for the C-4 methylene group of the cage diols and the cage ethers.

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Synthesis of 4-oxahexacyclo[5.4.1.02,6.03,10.05,9.08,11]dodecane-3-carboxylic acid

Cited by 13 publications

References 4 publications

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

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

Synthesis and NMR assignment of pentacycloundecane precursors of potential pharmaceutical agents

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