The influence of hydrate formation on the Clemmensen reduction of pentacyclo [5.4.0.02,6.03,10.05,9]undecane-8,11-dione and pentacyclo[6.4.0.02,7.03,11.06,10]dodecane-9,12-dione

Martins, Charles Ferreira; Viljoen, A. M.; Coetzee, M. S.; Fourie, L.; Wessels, Philippus L.

doi:10.1016/s0040-4020(01)96209-x

Cited by 29 publications

(8 citation statements)

References 7 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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“…Pentacyclo[6.3.0.0 2,6 .0 3,10 .0 5,9 ]undecane (trishomocubane) was first reported by Eaton et al in 1968, as a keto derivative. 1 Later, Underwood and Ramamoorthy were successful in synthesizing the underivatized C 11 H 14 polycyclic hydrocarbon, for which they proposed the trivial name trishomocubane (1) (Fig.…”

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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“…When the bridgeheads have different chemical shifts, the similarity of their resonances is in marked contrast to the variation observed in the splitting patterns for other proton pairs; the proton spectra of 3 ( Fig. 1) and of 4 (Fig. 2) show this clearly.…”

Section: Introductionmentioning

confidence: 79%

“…'The difficulties in dssigriirig the NMR spectra of substituted pzntacs~loC5. 4.0.0~.h.O".' ".05~q]undecaner (PCUDsI stem mainly from the very narrow chemical shift ranges exhibited by both the protons and carbons of the cage ctructure, particularly when the capr IS asymrrretrically substituted at the 8-and 11-positions Complete 'H arid I3C assignments have been made for sotnc symmetrically substituted P C U D S ,~.~ and for a m a l l number of asymmetrically substituted PCUDs such as i 1.1 1-di h y d rox ypen t acycl o [ S .4.0.…”

Section: Introductionmentioning

confidence: 99%

Complete assignment of the ¹H and ¹³C NMR spectra of a pentacyclo [5.4.0.0^2,6.0^3,10.0^5,9]undecane derivative

Cadd

Feast

Kenwright

et al. 1993

Magnetic Reson in Chemistry

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The production of compounds derived from intramolecular photocgcloaddition reactions upon Diels-Alder adducts has received considerable attention, but assignment of the NMR spectra of the photoaddition products has proved problematic, rendering structural determination difficult. This paper reports the complete assignments of the proton and carbon NMR spectra of 11.1 I-dimethoxypentacyclol S.~.0.02~6.0"".0".9 lundecan-&one and the assignment of the spectra of pentacyclo 1 5.4.0.02~6.0'~'0.05~9

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The influence of hydrate formation on the Clemmensen reduction of pentacyclo [5.4.0.02,6.03,10.05,9]undecane-8,11-dione and pentacyclo[6.4.0.02,7.03,11.06,10]dodecane-9,12-dione

Cited by 29 publications

References 7 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

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

Complete assignment of the ¹H and ¹³C NMR spectra of a pentacyclo [5.4.0.0^2,6.0^3,10.0^5,9]undecane derivative

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The influence of hydrate formation on the Clemmensen reduction of pentacyclo [5.4.0.02,6.03,10.05,9]undecane-8,11-dione and pentacyclo[6.4.0.02,7.03,11.06,10]dodecane-9,12-dione

Cited by 29 publications

References 7 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

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

Complete assignment of the 1H and 13C NMR spectra of a pentacyclo [5.4.0.02,6.03,10.05,9]undecane derivative

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Complete assignment of the ¹H and ¹³C NMR spectra of a pentacyclo [5.4.0.0^2,6.0^3,10.0^5,9]undecane derivative