13C, 15N CP-MAS, FT–IR and PM5 studies of some Schiff bases of gossypol in solid

Przybylski, Piotr; Schilf, Wojciech; Kamieński, Bohdan; Brzeziński, Bogumił; Bartl, Franz

doi:10.1016/j.molstruc.2004.11.045

Cited by 25 publications

(4 citation statements)

References 25 publications

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“…19) (35). The equilibrium between the various tautomeric Schiff's base structures (40a-c) has been extensively investigated by IR, NMR, and molecular modeling (125,(142)(143)(144)(145)(146)(147)(148)(149)(150)(151)(152)(153). For example, NMR experiments by Matlin and colleagues (144) on dianilinogossypol (R = -C 6 H 5 , Fig.…”

Section: Gossypol Reactionsmentioning

confidence: 99%

Reaction chemistry of gossypol and its derivatives

Kenar

2006

J Americ Oil Chem Soc

107

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Gossypol, a complex polyphenolic compound, is a naturally occurring highly colored yellow pigment found in the small intercellular pigment glands in the leaves, stems, roots, and seed of cotton plants. In cottonseed, gossypol contributes to its toxicity and therefore it is regarded as an unwanted processing component. It was not until its antitumor and male infertility activities were discovered that gossypol was considered as a valueadded natural product from cottonseed with useful physiological and chemical properties. These serendipitous discoveries created much excitement, and an enormous amount of research on gossypol has ensued. Since then, much research has focused on the preparation of suitable gossypol derivatives for medicinal applications. This review summarizes current knowledge about gossypol, its stereochemistry, tautomerism, and the many varied reactions the gossypol molecule can undergo.

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Section: Gossypol Reactionsmentioning

confidence: 99%

Reaction chemistry of gossypol and its derivatives

Kenar

2006

J Americ Oil Chem Soc

107

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“…It is interesting to note that in the relevant spectra of the Schiff bases, in which the enamine-enamine tautomeric forms were always observed, this signal was in the range of ca. 172 ppm, [26][27][28][29][30][31][32][33][34] whereas in the 13 C-NMR spectrum of gossypol hydrazones, in which N-imine-N-imine tautomers were always present, the corresponding signal was in the range of ca. 150 ppm.…”

Section: Nmr Studies Of Ghht and Its Complexes With The Monovalent Camentioning

confidence: 97%

“…104 and 161 ppm, respectively. [26][27][28][29][30][31][32][33][34] The signals of the protons from the thiophene parts arise as a triplet and two doublets in a narrow range of 7.92-7.23 ppm. The most shifted proton signal from this part arises as a doublet and can be assigned to the H 20 neighboring the oxygen atom of the carbonyl group due to anisotropy effect.…”

Section: Nmr Studies Of Ghht and Its Complexes With The Monovalent Camentioning

confidence: 99%

“…24,25 Hydrazones and Schiff bases of gossypol can be present in the two tautomeric forms that are analogous to the aldehydealdehyde and ketol-ketol tautomeric forms of gossypol. Recently, we have studied the structures of several Schiff bases of gossypol with L-amino acids, [26][27][28] crown ether amines, 28,29 oxaalkyl-amines, 28,30 n-butylamine, 31,32 tetrahydrofurfurylamine, 33 and allylamine. 34 All these articles reported the occurrence of the enamine-enamine tautomeric forms of gossypol Schiff bases both in solution and in the solid state.…”

Section: Introductionmentioning

confidence: 99%

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Multinuclear magnetic resonance, electrospray ionization–mass spectroscopy, and parametric method 5 studies of a new derivative of gossypol with 2‐thiophenecarbohydrazide as well as its complexes with LI⁺, Na⁺, K⁺, RB⁺, and Cs⁺ cations

et al. 2006

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A new derivative of racemic gossypol with 2-thiophenecarbohydrazide (GHHT) and its complexes with monovalent cations have been synthesized and studied by electrospray ionization-mass spectroscopy (ESI-MS), multinuclear nuclear magnetic resonance (NMR), as well as by the Parametric Method 5 (PM5) methods. It is demonstrated that GHHT forms stable complexes of 1:1 stoichiometry with monovalent metal cations. The structures of the complexes are stabilized by three types of intramolecular hydrogen bonds. The spectroscopic methods have provided clear evidence that GHHT and its complexes exist in the DMSO-d6 solution in the N-imine-N-imine tautomeric forms. The structures of the GHHT and its complexes with Li+, Na+, K+, Rb+, and Cs+ cations are visualized and discussed in detail.

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CP/MAS spectroscopy in the determination of the tautomeric forms of gossypol, its Schiff bases and hydrazones in the solid state

Przybylski

Schilf

Kamieński

et al. 2008

Magnetic Reson in Chemistry

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New Schiff bases and new hydrazones were synthesized and studied by (13)C and (15)N CP/MAS spectroscopy and by (1)H--(1)H COSY, (1)H--(13)C HMBC, (1)H--(13)C HSQC, (1)H--(15)N HMQC and (1)H--(15)N HSQC correlations. The CP/MAS investigation of gossypol has demonstrated that in the solid state it exists exclusively in the aldehyde-aldehyde tautomeric form. In contrast, CP/MAS studies of hydrazones and Schiff bases reveal that these compounds occur in the solid state in the N-imine-N-imine and enamine-enamine tautomeric forms, respectively. It is shown that the (13)C resonances of C-6, C-7 and C-11 carbon atoms are suitable for distinguishing between the tautomeric forms of aza-derivatives of gossypol in the solid state. Furthermore, we have proved that the (15)N CP/MAS spectra can be used to identify these tautomeric forms.

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13C, 15N CP-MAS, FT–IR and PM5 studies of some Schiff bases of gossypol in solid

Cited by 25 publications

References 25 publications

Reaction chemistry of gossypol and its derivatives

Reaction chemistry of gossypol and its derivatives

Multinuclear magnetic resonance, electrospray ionization–mass spectroscopy, and parametric method 5 studies of a new derivative of gossypol with 2‐thiophenecarbohydrazide as well as its complexes with LI⁺, Na⁺, K⁺, RB⁺, and Cs⁺ cations

CP/MAS spectroscopy in the determination of the tautomeric forms of gossypol, its Schiff bases and hydrazones in the solid state

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13C, 15N CP-MAS, FT–IR and PM5 studies of some Schiff bases of gossypol in solid

Cited by 25 publications

References 25 publications

Reaction chemistry of gossypol and its derivatives

Reaction chemistry of gossypol and its derivatives

Multinuclear magnetic resonance, electrospray ionization–mass spectroscopy, and parametric method 5 studies of a new derivative of gossypol with 2‐thiophenecarbohydrazide as well as its complexes with LI+, Na+, K+, RB+, and Cs+ cations

CP/MAS spectroscopy in the determination of the tautomeric forms of gossypol, its Schiff bases and hydrazones in the solid state

Contact Info

Product

Resources

About

Multinuclear magnetic resonance, electrospray ionization–mass spectroscopy, and parametric method 5 studies of a new derivative of gossypol with 2‐thiophenecarbohydrazide as well as its complexes with LI⁺, Na⁺, K⁺, RB⁺, and Cs⁺ cations