Studies on cyclitols—XVI

Steyn, R.; Sable, Henry Z.

doi:10.1016/s0040-4020(01)98156-6

Cited by 57 publications

(18 citation statements)

References 44 publications

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“…3 have been estimated for substituted cyclopentane systems (16): A = 9.5, B = 0.5, and C = 0.4. Substituting these coefficients predicts that the maximum coupling constant would be 10.4 Hz when -to = 1800.…”

Section: Methodsmentioning

confidence: 99%

Carbon-13 Relaxation and Proton Nuclear Magnetic Resonance Studies of Prostaglandin F _2α

Conover

Fried

1974

Proc. Natl. Acad. Sci. U.S.A.

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Carbon magnetic resonance T, relaxation and chemical shift measurements at 22.63 MHz establish hydrophobic aggregation of prostaglandin F2a in phosphate buffer solutions between 0.05 and 0.2 M. Analysis of the proton magnetic resonance spectra of prostaglandin F2a at 270 MHz by double resonance techniques yield all the proton-proton coupling constants for the five-membered ring indicating a favored half-chair conformation for the ring in which the dihedral angle for the C-8 and C-12 protons is close to 1800. Effective correlation times derived from carbon magnetic resonance T1 values for all the carbon atoms show segmental motion for ring carbon C-10 and in the aliphatic portions of both side chains, while the double bonded portions of the side chains and the ring carbons act as a more rigidly interconnected network. Chemical shift changes in the carbon magnetic resonance and proton magnetic resonance spectra upon aggregation suggest that the 5-6 double bond, C-7, and C-9 participate in the aggregation process.Previous work from this laboratory (1) and by others (2) has led to the assignment of all the resonances in the 1"C nuclear magnetic resonance (NMR) spectra of several of the natural prostaglandins and of some prostaglandin (PG) analogs. Our interest in the chemical and biological properties of the prostaglandins has prompted an extension of these studies to include 18C T1 measurements at 22.63 MHz and proton NMR spectra at 270 MHz with the aim of probing the conformation of these molecules in aqueous solution. A full x-ray crystallographic analysis of the tris-p-bromobenzoate of PGF1f, (3) and unit cell dimension measurements on PGE1 (4) show that the two side chains in these molecules are aligned parallel in close proximity to each other. Similar results were obtained with PGA1 (5) 2157 molecule similar to those described in this paper for PGF 2 in aqueous buffer. MATERIALS AND METHODSThe free PGF2a acid was prepared from its tris(hydroxymethyl)aminomethane salt, generously supplied by Dr. John Pike of the Upjohn Co., by acidification of its aqueous solution with hydrochloric acid to pH 3, followed by extraction with ethyl acetate, back-wash with water, and removal of the solvent in vacuo. All spectra were recorded using degassed solutions of PGF2a at concentrations ranging from 0.02 to 0.6 M in 0.05 M phosphate buffer in D20, adjusted to a pH meter reading of 7.2 with NaOH in D20 (corresponding to a pH of 7.6 in water) (8).The proton spectra were recorded at 200 on a Bruker HX-270 spectrometer operating at 270 MHz in the continuous wave mode. Field/frequency stabilization was obtained from the deuterium resonance of the solvent (D20). All chemical shifts are reported relative to external tetramethylsilane within L 0.02 ppm.The 18C spectra were obtained at a temperature of 34-36' using a Bruker HX-90E spectrometer operating at 22.63 MHz in pulsed Fourier transform mode. Field/frequency stabilization was obtained from the deuterium resonance of the solvent (D20). Proton decoupling was accomplished...

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Section: Methodsmentioning

confidence: 99%

Carbon-13 Relaxation and Proton Nuclear Magnetic Resonance Studies of Prostaglandin F _2α

Conover

Fried

1974

Proc. Natl. Acad. Sci. U.S.A.

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“…This conforination is preferred in various rigidly fused bicyclic cyclopentane derivatives (8). Table 1 12 (8). These latter structures have been shown to exist in the " V , boat" conforn~ation, and the similarity of the coupling constants for 11 to those observed in 7 allows one to assign the u hydroxyl of C-5 the same relative stereochemistry.…”

Section: La ~Nentzeloside (I) Rel-(i R4nr5r6r7s7ar) Epoxy-67-0mentioning

confidence: 95%

“…(see Fig. 2) to that of unedol diacetate (8) (5) coupled with the C-7a bridgehead proton ( J = 10 Hz). This signal was therefore the G-l acetal proton and the retention of the Large coupling indicated that the configuration at C-1 had not been affected by hydrolysis and acetylation.…”

Section: La ~Nentzeloside (I) Rel-(i R4nr5r6r7s7ar) Epoxy-67-0mentioning

confidence: 96%

“…The configuration of the C-5 proton could also be deduced from the observed coupling of 1.5 Hz. This is characteristic of a cis-interaction and the C-5 proton must therefore be placed cis to the C-6 epoxide proton (8).…”

Section: La ~Nentzeloside (I) Rel-(i R4nr5r6r7s7ar) Epoxy-67-0mentioning

confidence: 99%

“…Dreiding models show that this is only possible if these protons are trans and the cyclopentane ring has a " V , boat" conformation. This conforination is preferred in various rigidly fused bicyclic cyclopentane derivatives (8). Table 1 12 (8).…”

Section: La ~Nentzeloside (I) Rel-(i R4nr5r6r7s7ar) Epoxy-67-0mentioning

confidence: 99%

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Iridoids of Mentzelia decapetala (Pursh). I. Mentzeloside

Danielson¹,

Hawes²,

Bliss³

1973

Can. J. Chem.

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Mentzeloside (I), rel-(lR,4aR,5R,6R,7S,7aR)-6,7-epoxy-1-O-~-~-glucosyl-5-hydroxy-l,4a,5,6,7,7a-hexahydro-4-methylcyclopenta(c)pyran, was isolated from flowers and seed pods o f Mentzelia decnpetala. T h e preparation o f various chemical derivatives and the examination o f spectral (i.r., u.v., and 'H n.m.r.) data allowed a complete structure t o be proposed for the title compound. -5, hexahydro-1,4a,5,6,7,7a methyl-4 cyclopenta(c) La ~nentzeloside (I), rel-(I R,4nR,5R,6R,7S,7aR) epoxy-6,7-0-B-D-glucosyl-1 hydroxy

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Synthesis and Ring-Opening Reactions of the Diastereoisomericcis- andtrans-Epoxides Derived from 3-(Benzyloxy)cyclopentene and 2-(Benzyloxy)-2,5-dihydrofuran

Crotti¹,

Bussolo

Favero

et al. 1998

Eur. J. Org. Chem.

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Studies on cyclitols—XVI

Cited by 57 publications

References 44 publications

Carbon-13 Relaxation and Proton Nuclear Magnetic Resonance Studies of Prostaglandin F _2α

Carbon-13 Relaxation and Proton Nuclear Magnetic Resonance Studies of Prostaglandin F _2α

Iridoids of Mentzelia decapetala (Pursh). I. Mentzeloside

Synthesis and Ring-Opening Reactions of the Diastereoisomericcis- andtrans-Epoxides Derived from 3-(Benzyloxy)cyclopentene and 2-(Benzyloxy)-2,5-dihydrofuran

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Studies on cyclitols—XVI

Cited by 57 publications

References 44 publications

Carbon-13 Relaxation and Proton Nuclear Magnetic Resonance Studies of Prostaglandin F 2α

Carbon-13 Relaxation and Proton Nuclear Magnetic Resonance Studies of Prostaglandin F 2α

Iridoids of Mentzelia decapetala (Pursh). I. Mentzeloside

Synthesis and Ring-Opening Reactions of the Diastereoisomericcis- andtrans-Epoxides Derived from 3-(Benzyloxy)cyclopentene and 2-(Benzyloxy)-2,5-dihydrofuran

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About

Carbon-13 Relaxation and Proton Nuclear Magnetic Resonance Studies of Prostaglandin F _2α

Carbon-13 Relaxation and Proton Nuclear Magnetic Resonance Studies of Prostaglandin F _2α