The clemmensen reduction of pentacyclo [6.4.0.02,7.03,11.06,10]dodecane-9,12-dione

Martins, Charles Ferreira; Fourie, L.; Venter, H.J.T.; Wessels, Philippus L.

doi:10.1016/s0040-4020(01)85443-0

Cited by 14 publications

(5 citation statements)

References 11 publications

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“…10,17 The diene diol 2 is normally synthesized with excess Grignard reagent. When the reaction was accidentally performed with a ratio of 1 : 1 Grignard reagent : dione (1), an unknown compound (5) was isolated. Attempts to elucidate the structure of the unknown compound using 2D NMR techniques proved to be extremely difficult, if not impossible, even with the aid of MS results, m/z 415 [M C H] C .…”

Section: Introductionmentioning

confidence: 99%

NMR assignments of a di‐pentacyclo‐undecane cyclic ether

Kruger

Ramdhani

2006

Magnetic Reson in Chemistry

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The X-ray structure of a di-pentacyclo-undecane cyclic ether was recently reported. As part of a programme to use NMR spectroscopy for the structure elucidation of cage compounds, the complete NMR assignments of the cyclic ether was attempted. Major overlap of proton and carbon signals of the two cages is observed. It was required to elucidate the fragment analogues that represent similar structural features of the cyclic ether in order to get an approximate but reasonable insight into the complex overlapping signals. Normal 2D NMR techniques were utilized to assign the various NMR signals.

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Section: Introductionmentioning

confidence: 99%

NMR assignments of a di‐pentacyclo‐undecane cyclic ether

Kruger

Ramdhani

2006

Magnetic Reson in Chemistry

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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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“…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). 15 This method was previously successfully applied to adamantanone 19 and to pentacyclo-undecanone.…”

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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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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The clemmensen reduction of pentacyclo [6.4.0.02,7.03,11.06,10]dodecane-9,12-dione

Cited by 14 publications

References 11 publications

NMR assignments of a di‐pentacyclo‐undecane cyclic ether

NMR assignments of a di‐pentacyclo‐undecane cyclic ether

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

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

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