scholarly journals Competitive Diels–Alder and ene addition of N-arylmaleimides to 7-dehydrocholesteryl acetate

1992 ◽  
Vol 70 (11) ◽  
pp. 2730-2744 ◽  
Author(s):  
William J. Leigh ◽  
Donald W. Hughes ◽  
D. Scott Mitchell
Keyword(s):  
Molecular Mechanics ◽  
Nmr Spectra ◽  
Benzene Solution ◽  
Diels Alder ◽  
Spectroscopic Techniques ◽  
Two Dimensional ◽  
A Minor ◽  
C Nmr ◽  
Alder Adduct ◽  
Ene Addition

Thermolysis of N-phenyl, N-para-biphenyl, and N-para, para′-terphenylmaleimide with 7-dehydrocholesteryl acetate in benzene solution at 200 °C yields mixtures of four cycloadducts in relative yields that are essentially independent of the maleimide substituent. The three major products are those of ene addition to C7 of the steroid with abstraction of the proton at C9 or C14. The α-endo-Diels-Alder adduct is formed as a minor product. The structures of the adducts have been elucidated on the basis of one- and two-dimensional 1H and 13C NMR spectroscopic techniques, including homonuclear 1H decoupling, NOE, 1H–1H COSY, heteronuclear 1H–13C shift correlation, and TOCSY 2-D experiments, and the results of molecular mechanics (MMX) calculations. The combination of these techniques has made it possible to almost completely assign the 1H and 13C NMR spectra for two of the ene adducts and the Diels–Alder adduct from reaction of 7-dehydrocholesteryl acetate with N-phenyl maleimide.

Structural studies of digitoxin and related cardenolides by two-dimensional NMR

1990 ◽  
Vol 68 (2) ◽  
pp. 272-277 ◽  
Author(s):  
Torbjörn Drakenberg ◽  
Peter Brodelius ◽  
Deane D. McIntyre ◽  
Hans J Vogel
Keyword(s):  
Nmr Spectroscopy ◽  
Nmr Spectra ◽  
Chair Conformation ◽  
Coupling Constants ◽  
Two Dimensional ◽  
Structural Studies ◽  
Solution Conformation ◽  
Phase Sensitive ◽  
Multiple Relay ◽  
C Nmr

The 1H and 13C NMR spectra of the cardenolides digitoxigenin, digoxigenin, digitoxin, and mono- and bis-digitoxigenin digitoxosides have been completely assigned by two-dimensional NMR spectroscopy. The techniques used include phase-sensitive COSY, multiple relay COSY, and carbon–proton correlation (HETCOR and HMQC) spectra. Various aspects of the solution conformation of the steroid moiety of digitoxin and digoxigenin could be determined from coupling constants and NOE difference experiments and they are indicative of an all-chair conformation. The carbohydrate rings in digitoxin and the mono- and bis-digitoxigenin digitoxosides are also in the chair conformation. Keywords: cardenolides, digitoxigenin, digitoxin, 2-dimensional NMR, conformational analysis.

scholarly journals A New Bioactive Steroidal Saponin from Leaves of Furcraea gigantea

2006 ◽  
Vol 61 (9) ◽  
pp. 1153-1157 ◽  
Author(s):  
Bernadete P. da Silva ◽  
José P. Parente
Keyword(s):  
Nmr Spectra ◽  
Capillary Permeability ◽  
Structural Identification ◽  
2D Nmr ◽  
In Vitro Assays ◽  
Steroidal Saponin ◽  
Spectroscopic Techniques ◽  
C Nmr

Abstract A new bidesmosidic furostanol saponin was isolated from leaves of Furcraea gigantea Vent. Its structure was established as 3-[(O-6-deoxy-α-L-mannopyranosyl-(1→4)-O-β -D-glucopyranosyl-( 1→3)-O-[O-β -D-glucopyranosyl-(1→3)-β -D-glucopyranosyl-(1→2)-O-β -D-glucopyranosyl- (1→4)-β -D-galactopyranosyl)oxy]-(3β ,5α,15α,22α,25R)-26-(β -D-glucopyranosyloxy)-15,22-dihydroxy- furost-12-one. Its structural identification was performed using detailed analyses of 1H and 13C NMR spectra including 2D NMR spectroscopic techniques (DEPT, COSY, HETCOR and COLOC) and chemical conversions. The steroidal saponin showed no haemolytic effects in the in vitro assays and demonstrated inhibition of the capillary permeability activity.

scholarly journals New Steroidal Saponins from Rhizomes of Costus spiralis

2004 ◽  
Vol 59 (1-2) ◽  
pp. 81-85 ◽  
Author(s):  
Bernadete P. da Silva ◽  
José P. Parente
Keyword(s):  
Nmr Spectra ◽  
2D Nmr ◽  
Inflammatory Activity ◽  
Spectroscopic Techniques ◽  
Steroidal Saponins ◽  
Anti Inflammatory ◽  
C Nmr

Two new steroidal saponins were isolated from the rhizomes of Costus spiralis Rosc. Their structures were established as (3β,25R)-26-(β-ᴅ-glucopyranosyloxy)-22-hydroxyfurost-5- en-3-ylO-d-apio-β-ᴅ-furanosyl-(1→2)-O-[α-ʟ-rhamnopyranosyl-(1→4)]-β-ᴅ-glucopyranoside (1) and (3β,25R)-26-(β-ᴅ-glucopyranosyloxy)-22-hydroxyfurost-5-en-3-yl O-ᴅ-apio-β-ᴅ-furanosyl-( 154)-O-[α-ʟ-rhamnopyranosyl-(1→2)]-β-ᴅ-glucopyranoside (2). Their structural identifications were performed using detailed analyses of 1H and 13C NMR spectra including 2D NMR spectroscopic techniques (DEPT, COSY, HETCOR and COLOC) and chemical conversions. The steroidal saponins were evaluated for anti-inflammatory activity.

Synthèse, structure et études spectroscopiques RMN 1H et 13C de dérivés perhydrocyclododéca[b]furaniques

1991 ◽  
Vol 69 (3) ◽  
pp. 521-527 ◽  
Author(s):  
Michel Albrand ◽  
René Dolmazon ◽  
Patrick Pollet
Keyword(s):  
Conformational Analysis ◽  
Force Field ◽  
Key Words ◽  
Molecular Mechanics ◽  
Trans Isomer ◽  
Nmr Spectra ◽  
Synthetic Route ◽  
Force Field Calculations ◽  
Cis Isomer ◽  
C Nmr

A synthetic route to perhydrocyclododeca[b]furan-3-ols, perhydrocyclododeca[b]furan-3-ones, and perhydrocyclododeca[b]furan derivatives is described. Their configurations were determined. For the perhydrocyclododeca[b]furan-3-one and perhydrocyclododeca[b]furan pairs, the cis isomer was much less stable than the trans isomer. This agrees well with results from a conformational analysis, carried out by molecular mechanics. The 1H and l3C NMR spectra are reported. Key words: perhydrocyclododeca[b]furans, conformations, force field calculations, 1H and 13C NMR.

Direct NMR evidence for the equivalent participation of L-phenylalanine and L-tyrosine in the biosynthesis of the intermolecular Diels–Alder type adducts of prenylchalcone and prenylated 2-arylbenzofuran in Morus alba cell cultures

1994 ◽  
Vol 72 (1) ◽  
pp. 12-14 ◽  
Author(s):  
Yoshio Hano ◽  
Taro Nomura ◽  
Shinichi Ueda
Keyword(s):  
Amino Acids ◽  
Cell Cultures ◽  
Nmr Spectra ◽  
Diels Alder ◽  
Morus Alba ◽  
High Yields ◽  
C Nmr

L-[3-13C]Phenylalanine and L-[3-13C]tyrosine were administered to Morus alba cell cultures, to produce intermolecular Diels–Alder type adducts of a prenylchalcone and a 2-arylbenzofuran such as chalcomoracin (1) as well as the adducts of two molecules of prenylchalcones such as kuwanon J (2) in high yields. The 13C NMR spectra of 1 and 2 isolated from the cultures revealed that both amino acids were incorporated intact into chalcomoracin (1) and kuwanon J (2). This is the first example of direct NMR evidence for the almost equivalent incorporation of phenylalanine and tyrosine into the shikimate metabolites. This finding suggests the participation of a biosynthetic route from phenylalanine via trans-cinnamate to p-coumarate and from tyrosine to p-coumarate in this plant.

Two Dimensional 1H–1H and 13C–1H-Correlation NMR: The Analysis of η3-Allylnickel Complexes

1982 ◽  
Vol 37 (8) ◽  
pp. 1054-1057 ◽  
Author(s):  
Reinhard Benn
Keyword(s):  
Nmr Spectra ◽  
Nickel Complexes ◽  
Routine Analysis ◽  
Two Dimensional ◽  
Nmr Techniques ◽  
C Nmr

Abstract The 1H and 13C NMR spectra of various alkylsubstituted η3-allyl-η5-cyclopentadienyl-nickel complexes were analysed with the help of two dimensional correlation (1H-1H and 1H-13C) NMR. The use of two dimensional NMR techniques for the routine analysis of complicated NMR spectra is demonstrated.

Chemistry of chromotropic acid. 1H and 13C NMR spectroscopy of chromotropic acid and its derivatives

1991 ◽  
Vol 69 (8) ◽  
pp. 1207-1211 ◽  
Author(s):  
Paris E. Georghiou ◽  
Chi Keung (Jimmy) Ho ◽  
Chester R. Jablonski
Keyword(s):  
Nmr Spectroscopy ◽  
13C Nmr ◽  
Nmr Spectra ◽  
Deuterium Oxide ◽  
13C Nmr Spectroscopy ◽  
Chromotropic Acid ◽  
Hydroxyl Groups ◽  
Two Dimensional ◽  
1H And 13C Nmr ◽  
C Nmr

The 1H and 13C NMR spectra of chromotropic acid (CTA) (4,5-dihydroxy-2,7-naphthalenedisulphonic acid) have been unambiguously assigned. Proton NOED spectra were used to show the proximity of both H-3 and H-6 and the hydroxyl groups. Two-dimensional 1H–13C NMR correlation spectra of CTA, of its corresponding diacetoxy derivative, and of 3-bromo- and 3,6-dibromo-CTA support the assignments. A regioselective deuterium exchange reaction of the C-3 and C-6 protons of CTA with deuterium oxide was observed during the NMR experiments. This latter finding is strongly indicative of the mode of formation, and of the nature of the chromogen formed in the reaction of CTA with formaldehyde in the well-known CTA-formaldehyde analytical reaction. Key words: chromotropic acid, 3-bromochromotropic acid, 3,6-dibromochromotropic acid.

Annelated furans. XI. The reactions of 2-vinylfurans with acetylenic esters

1973 ◽  
Vol 26 (5) ◽  
pp. 1059 ◽  
Author(s):  
WJ Davidson ◽  
JA Elix
Keyword(s):  
Diels Alder ◽  
Dimethyl Acetylenedicarboxylate ◽  
Acetylenic Ester ◽  
Acetylenic Esters ◽  
Methyl Propiolate ◽  
Diene System ◽  
Alder Adduct ◽  
Ene Addition

In general dimethyl acetylenedicarboxylate and methyl propiolate have been found to react with 2-vinylfurans to give the corresponding dimethyl benzofuran-4,5-di-carboxylates and methyl benzofuran-4- carboxylates respectively. In several instances dimethyl acetylenedicarboxylate did not react exclusively with the exocyclic diene system of the 2-vinylfuran and here the corresponding dimethyl 3,6-epoxy-3-vinyl-3,6-dihydrophthalates were obtained by Diels-Alder addition to the furanoid diene system. At 80� 2-vinylfuran and dimethyl acetylenedicarboxylate formed the 1 : 2 adduct (11), the formation of which can be interpreted as involving an ene addition of a second mole of the acetylenic ester to the initially formed Diels-Alder adduct.

A New Bioactive Steroidal Saponin from Agave attenuata

2002 ◽  
Vol 57 (5-6) ◽  
pp. 423-428 ◽  
Author(s):  
Bernadete P. da Silva ◽  
Allyne C. de Sousa ◽  
Graziela M. Silva ◽  
Tatiana P. Mendes ◽  
José P. Parente
Keyword(s):  
Nmr Spectra ◽  
Capillary Permeability ◽  
Structural Identification ◽  
2D Nmr ◽  
Inflammatory Activity ◽  
Steroidal Saponin ◽  
Spectroscopic Techniques ◽  
Anti Inflammatory ◽  
Permeability Assay ◽  
C Nmr

A new steroidal saponin was isolated from the leaves of Agave attenuata Salm-Dyck. Its structure was established as (3β,5β,22α,25S)-26-(β-ᴅ-glucopyranosyloxy)-22-methoxyfurostan- 3-yl O-β-ᴅ-glucopyranosyl-(1→2)-β-ᴅ-glucopyranosyl-(1→2)-O-[β-ᴅ-glucopyranosyl- (1→3)]-β-ᴅ-glucopyranosyl-(1→4)-β-ᴅ-galactopyranoside. The structural identification was performed using detailed analyses of 1H and 13C NMR spectra including 2D NMR spectroscopic techniques (COSY, HETCOR and COLOC) and chemical conversions. The haemolytic potential of the steroidal saponin was evaluated and the anti-inflammatory activity was performed using the capillary permeability assay.

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