Synthesis of 2-substituted pentacyclo[6.3.0.02,6.03,10.05,9]undecanes (D3-trishomocubanes) and a study of their13C spin–lattice relaxation times in solution

Schwartz, M.; Marchand, Alan P.; Wang, Kuen-Shian; Reddy, Santhi; Redda, G. Madhusudhan; Gadgil, V. R.; Watson, William H.; Kashyap, R. P.; Krawiec, Mariusz

doi:10.1039/p29930001829

Cited by 4 publications

(6 citation statements)

References 21 publications

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“…It was evident that 6 had been synthesized owing to the presence of four carbonyl groups present in the 13 C NMR spectrum. The absence of the amide and imide protons of the hydantoin ring at ¾6 and ¾10 ppm, respectively, in the 1 H NMR spectrum and the presence of the expected molecular ion peak of m/z 431 [M C H C ] in the mass spectrum further supported the presence of two Boc groups.…”

Section: Resultsmentioning

confidence: 98%

“…The 13 C NMR spectrum exhibits a characteristic 10 amide carbonyl signal (C-4 0 at 177.50 ppm) and a urea carbonyl group (C-2 0 at 157.05 ppm), the eight methine carbons of the cage between 39.57 and 55.67 ppm and the presence of two methylene carbons at 32.95 and 33.49 ppm. Two-dimensional NMR techniques were essential for the full elucidation of the trishomocubane hydantoin.…”

Section: Resultsmentioning

confidence: 99%

“…It is evident that the mono-Boc derivative (5) of the hydantoin had been synthesized with the appearance of three carbonyl peaks in the 13 C NMR spectrum and the expected molecular ion peak of m/z 331 [M C H C ] in the mass spectrum. The presence of a proton peak (1.56 ppm) in the 1 H NMR spectrum, which integrates to nine protons, could, therefore, be assigned to the three methyl groups (H-8 0 ) of the Boc group.…”

Section: Resultsmentioning

confidence: 99%

“…The HMBC correlation between H-12 0 and the carbon peak at 84.95 ppm allows it to be assigned to C-11 0 . The C-4 0 carbonyl is assigned to 169.58 ppm in the 13 C NMR spectrum and the C-2 0 carbonyl is assigned to 145.74 ppm owing to more electron delocalization from N-1 0 and N-3 0 at C-2 0 . Based on the same analogy, C-5 0 and C-9 0 carbonyl groups could possibly be assigned to 149.67 and 149.03 ppm, respectively.…”

Section: Resultsmentioning

confidence: 99%

“…Two-dimensional NMR techniques were essential for the full elucidation of the trishomocubane hydantoin. C-4 of the cage is assigned to 73.48 ppm in the 13 C NMR spectrum owing to it being an integral part of the electron-withdrawing hydantoin ring system. This assignment is confirmed by the absence of heteronuclear single quantum coherence (HSQC) correlations and the presence of heteronuclear multiple bond coherence (HMBC) correlations with NH-1 0 of the hydantoin ring.…”

Section: Resultsmentioning

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: Resultsmentioning

confidence: 98%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

See 3 more Smart Citations

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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ChemInform Abstract: Synthesis of 2‐Substituted Pentacyclo(6.3.0.02,6.03,10.05,9)undecanes ( D3‐Tris‐homocubanes) and a Study of Their 13C Spin‐Lattice Relaxation Times in Solution.

et al. 1994

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Synthesis of 2-Substituted Pentacyclo(6.3.0.02,6.03,10.05,9)undecanes ( D3-Tris-homocubanes) and a Study of Their 13C Spin-Lattice Relaxation Times in Solution.-In order to determine the effects of temp. and intermolecular interactions on the reorientational dynamics in 2-substituted tris-homocubanes, a series of 4 title compounds is prepared. The synthesis of (XIa) is outlined in the scheme, (XIb)-(XId) are obtained by standard methods. 13C NMR spin-lattice relaxation times and nuclear Overhauser enhancements of various skeletal carbon atoms in these compounds and the unsubstituted derivative (XIe) are measured as a function of temp. in CHCl3. -(SCHWARTZ, M.; MARCHAND, A. P.; WANG, K.-S.; REDDY, S. P.; REDDA, G. M.; GADGIL, V. R.; WATSON, W. H.; KASHYAP, R. P.; KRAWIEC, M.; J.

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4,7,11‐Triheterotrishomocubanes – Propeller‐Shaped Highly Symmetrical Chiral Molecules Derived from Barrelene

et al. 2006

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Keywords: Barrelene / Chirality / Epoxidation / Rearrangement / Small ring systems / Structure elucidation Epoxidation of barrelene (3) with a neutralized solution of Oxone ® gave the barrelene trisepoxide 6 in 82 % isolated yield, while lead tetraacetate promoted aziridination of 3 with two equiv. of N-aminophthalimide gave a mixture of mono-7 and bis(aziridine) endo,exo-8, which were isolated in 67 and 8 % yield, respectively. Fourfold repetition of this aziridination gave the bis(aziridines) exo,exo-and endo,exo-8 along with the trisaziridine 9 in 21, 8 and 19 % yield, respectively. Epoxidation of 7 and endo,exo-8 with buffered m-chloroperbenzoic acid furnished the dioxaazatrishomobarrelene 10 and oxadiazatrishomobarrelene 11 in 36 and 62 % yield, respectively. The structures of triheteratrishomobarrelenes 6 and 9 were established by X-ray crystallography. Upon treatment with BF 3 ·Et 2 O at -20°C (for 6) or with the strongly acidic ion exchange resin Amberlyst 15 at ambient or elevated temperatures (for 9-11), these triheteratrishomobarrelenes rearrange to give the triheteratrishomocubanes rac-12 to rac-15, as proved by X-ray crystal structure analysis of rac-13, in 75-100 % yield. The enantiomeric pairs of trioxa-12 and triazatrishomocubane 13 were separated by prepara-

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Synthesis of 2-substituted pentacyclo[6.3.0.0^2,6.0^3,10.0^5,9]undecanes (D₃-trishomocubanes) and a study of their¹³C spin–lattice relaxation times in solution

Cited by 4 publications

References 21 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

ChemInform Abstract: Synthesis of 2‐Substituted Pentacyclo(6.3.0.02,6.03,10.05,9)undecanes ( D3‐Tris‐homocubanes) and a Study of Their 13C Spin‐Lattice Relaxation Times in Solution.

4,7,11‐Triheterotrishomocubanes – Propeller‐Shaped Highly Symmetrical Chiral Molecules Derived from Barrelene

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