Determination of the configuration and conformation of .alpha.-, .beta.-, and isotripiperideine carbon-13 nuclear magnetic resonance spectroscopy

Kessler, Horst; Moehrle, H.; Zimmermann, Gottfried

doi:10.1021/jo00421a013

Cited by 30 publications

(9 citation statements)

References 4 publications

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“…Pure aldimine 5 was found to be surprisingly stable; even in highly concentrated solutions at room temperature there was no tendency for trimerization. [24] In line with prior experience, [25] cycloaddition experiments with 5 -with approaches to the diene ring from both sides being sterically hindered and high-pressure facilities [26] not yet being available -were only successful with the extremely reactive triazolinedione 6 (NMTD). The very fast reaction (even at -60°C) proceeded stereospecifically in an exo fashion and led quantitatively to 7.…”

Section: Choice Of Substrates -General Aspectsmentioning

confidence: 76%

Proximate,syn-Periplanar, Rigid Imine(Nitrone)/Ene-, and Diazene(Diazeneoxy)/Ene Systems: Syntheses, Homoconjugate Reactivity and Photochemistry

Fischer¹,

Fritz

Rihs

et al. 2000

Eur. J. Org. Chem.

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The chances for intramolecular imine/ene (→ azetidines), diazene/ene (→ 1,2‐diazetidines), diazeneoxy/ene (→ 1,2‐diazetidine oxides) and diazenedioxiene (→ 1,2‐diazetidine dioxides) [2+2]photocycloadditions and for the isolation of the respective photoproducts, have been probed with specifically designed substrates. Upon direct or sensitized excitation, [2+2]cycloaddition was found to be the exclusive or at least dominant chemical process for the CN/CC, NN/CC and ONN(O)/CC systems featuring very small π,π‐distances of 2.8‐3.0 Å and large π,π‐interorbital angles of 160‐170° (7 → 51, 17 → 55, 33 → 58 (competing N2 elimination), 22 → 62). This is not the case, however, in ONNO/CC (23, where electron transfer is a possibility), or in the more flexible, less “proximate” CN/CN (57) and CNO/CN (63) systems (π,π‐distances of >3.8 Å). While the corseted 1,2‐diazetidine photoadducts (55, 58) proved to be thermally stable, their N‐oxides (62, 65) were thermally too labile to be directly observable above ‐65 °C. For the latter's only fleeting existence, electronic rather than strain effects are held responsible (B3LYP/6‐31G* calculations). Very facile CNO/CC (12 → 13) and NNO/CC (22 → 24) [3+2]cycloadditions, homoconjugate addition of H2 and of dienophiles ([2+2+2]) to the diazene/ene 17 (→ 39, 41, 45) are manifestations of “proximity” in these bichromophoric skeletons.

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Section: Choice Of Substrates -General Aspectsmentioning

confidence: 76%

Proximate,syn-Periplanar, Rigid Imine(Nitrone)/Ene-, and Diazene(Diazeneoxy)/Ene Systems: Syntheses, Homoconjugate Reactivity and Photochemistry

Fischer¹,

Fritz

Rihs

et al. 2000

Eur. J. Org. Chem.

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“…The spectral properties of the crystals were identical to those reported by Kessler et al for α-tripiperideine. [18] Condensation between ∆ 1 -Piperideine (9) and Diethyl Malonate (DEM): A fresh solution of ∆ 1 -piperideine in ethanol/diethyl ether was concentrated to dryness, and the residue was dissolved in water (10 mL). Aqueous HCl (1 ) was added dropwise at 0°C until the desired pH was reached, and diethyl malonate (1.266 g, 7.91 mmol, or 2.532 g, 15.83 mmol) was then poured into the solution in one portion.…”

mentioning

confidence: 99%

Synthesis of New Analogues of the Tetraponerines

Rouchaud

Braekman

2009

Eur J Org Chem

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To evaluate the influences of the tetraponerine alkyl chains and tricyclic ring systems on their cytotoxic activities, we have prepared a series of alkyl derivatives (3a, 3b and 4a–f) of the non‐natural tricyclic skeletons decahydro‐2H,6H‐dipyrido[1,2‐a:1′,2′‐c]pyrimidine (3, 6–6–6 skeleton) and dodecahydro‐2H‐1,8a‐diazaphenanthrene (4, iso‐6–6–6 skeleton). In this study, two ways to synthesise the 6–6–6 analogues have been developed and compared. One is based on the condensation of α‐tripiperideine with diethyl malonate (DEM) in water at pH 11. This yielded oxo ester 11, precursor of the amino nitrile 8, but only in moderate yield. In the second pathway, the key intermediate 8 was more efficiently synthesised by starting from 2‐(2‐piperidyl)ethanol. Treatment of 8 with alkyl Grignard reagents led to the 6–6–6 analogues 3a and 3b. When the one‐pot reaction between α‐tripiperideine and DEM was performed in water at pH 8, the lactam 12, precursor of the iso‐6–6–6 skeleton, was obtained in a yield of 76 %. The same lactam was also obtained in a yield of 86 % by treatment of tetrahydroanabasine 14 with DEM in water at pH 8. Lactam 12 was transformed into the iso‐6–6–6 analogues 4a–4f. The cytotoxic activities of the 6–6–6 and iso‐6–6–6 analogues against HT29 cancer cells were compared with those of the 5–6–5 and 6–6–5 tetraponerines and with those of solenopsin analogues. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

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“…Labile trimer 20 is known to rearrange into stable trimer 21 which arises from the dimerization of two tetrahydropyridine ( 4 ) units into tetrahydroanabasine ( 7 ) followed by the condensation of a third 4 molecule (Scheme ) 8. This rearrangement takes place in a rather spontaneous fashion.…”

Section: Self‐condensations Of Tetrahydropyridine and Glutaraldehydementioning

confidence: 99%

Manipulating Simple Reactive Chemical Units: Fishing for Alkaloids from Complex Mixtures

Poupon

Gravel

2015

Chemistry A European J

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This Concept article describes how key C10 molecular scaffolds, too reactive to be obtained through classical multistep synthesis, were targeted in the most simple reaction conditions, reproducing those that may be encountered in living cells. The rationale was that small amounts of these reactive intermediates might be formed in situ from cheap and abundant reactants (i.e., glutaraldehyde and tetrahydropyridine) resulting, upon further rearrangement in "complex mixtures" from which natural substances would arise. From five types of mixtures, at least six full carbon skeletons of known natural substances were formed spontaneously. This work also led to the discovery of new plausible biosynthetic achiral precursors in the Nitraria metabolism.

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Determination of the configuration and conformation of .alpha.-, .beta.-, and isotripiperideine carbon-13 nuclear magnetic resonance spectroscopy

Cited by 30 publications

References 4 publications

Proximate,syn-Periplanar, Rigid Imine(Nitrone)/Ene-, and Diazene(Diazeneoxy)/Ene Systems: Syntheses, Homoconjugate Reactivity and Photochemistry

Proximate,syn-Periplanar, Rigid Imine(Nitrone)/Ene-, and Diazene(Diazeneoxy)/Ene Systems: Syntheses, Homoconjugate Reactivity and Photochemistry

Synthesis of New Analogues of the Tetraponerines

Manipulating Simple Reactive Chemical Units: Fishing for Alkaloids from Complex Mixtures

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