Analyse des spectres de RMN du proton des dichlorocyclopentènes symétriques

Lemarié, Bernard; Lasne, Marie‐Claire

doi:10.1016/0584-8539(76)80083-9

Cited by 8 publications

(1 citation statement)

References 51 publications

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“…as in the case of nucleo~ides.~ A more suitable method for the analysis of flexible fivemembered rings is the extended R value method. 16 The average value of the endocyclic torsion angle wij is related to the R y = Jij,avrra"s/Jij,avcis ratio through relationship (2) where x is a JViC < , 6.12 Hz, and nearly equal values of Jcis and P'""" for this Rij -Kcos2x tgZ Wij,av = Ksin2x projection angle of the methylene group in the i position on a plane perpendicular to the ij bond, and K is a constant related to the parameters of the Karplus equation. Lambert ' 7 * 1 * has suggested the usefulness of the R value method in the case of electronegative substituents attached to the ring.…”

Section: Resultsmentioning

confidence: 99%

Sterically crowded five-membered heterocyclic systems. Part 2. Conformation of 2,2,5,5-tetramethylpyrrolidin-3-ol from nuclear magnetic resonance spectroscopy, crystal structure, and molecular mechanics calculations

Cygler¹,

Dobrynin²,

Grabowski³

et al. 1985

J. Chem. Soc., Perkin Trans. 2

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Section: Resultsmentioning

confidence: 99%

Sterically crowded five-membered heterocyclic systems. Part 2. Conformation of 2,2,5,5-tetramethylpyrrolidin-3-ol from nuclear magnetic resonance spectroscopy, crystal structure, and molecular mechanics calculations

Cygler¹,

Dobrynin²,

Grabowski³

et al. 1985

J. Chem. Soc., Perkin Trans. 2

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Synthèse de composés cyclopentaniques chiraux, di, tri et tétrasubstitués. Application à la synthèse de dérivés Oxa‐13‐prostanoïques

Barrière

Cléophax

Géro

et al. 1983

Helvetica Chimica Acta

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SummaryThe cyclopentenecarbaldehyde la, acetals 2 a, 2 b and the cyclopentenone 2 c have been transformed through regio and stereocontrolled reactions into a variety of enantiomerically pure substituted cyclopentanes. Using appropriately selected Wittig reagents, aldehyde l a furnished the condensation products 3, 4, 5. Michael addition of diethyl malonate on the a,p-unsaturated aldehyde l a under phasetransfer conditions led efficiently to 7. Reduction of the cyclopentenone 2 c gave 21 in high yield. The cyclopentenes 2a, 2b and 23, submitted to hydroborationoxidation furnished the cyclopentanols 10,13 and 24, respectively, in 30, 70 and 50% yields, reflecting the substitution pattern of the starting alkenes. The salient feature of these reactions is the stereospecificity due to the chiral centre of the molecules la, 2 a , 2b and 2c, leading to compounds with two, three and four asymmetric centres. The straightforward synthesis of 1 la-hydroxy-13-oxaprostanoic acid 20 is described and an approach towards the preparation of 9 a , 1 la-dihydroxy-13-oxaprostanoic acid 34 is also presented. The structure of these products has been determined by 'H-and 13C-NMR spectroscopy.Introduction. -Un effort considkrable a ttC dkploye durant les dix dernieres annees pour la preparation d'analogues de prostaglandines plus stables et a activite plus specifique que les composks naturels [ 11. Cependant, si la plupart des synthhes rkaliskes utilisent des resolutions [2] ou des transformations enzymatiques [3], une des mkthodes de choix pour la synthese de composks knantiomkriquement purs est l'emploi d'un produit de depart nature1 chiral [4]. Nous avons rkcemment decrit [5] la synthese de cyclopentenes chiraux du type I et 11, partir de l'acide D ( -) -quinique et decrivons, dans ce memoire, quelques-unes de leurs transformations ainsi que leur utilisation pour la synthese d'analogues oxa-13 de l'acide

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A case of negative homoallylic coupling constants: 3‐cyclopentenone

Lemarié

Ripoll

1977

Org. Magn. Reson.

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Analyse des spectres de RMN du proton des dichlorocyclopentènes symétriques

Cited by 8 publications

References 51 publications

Sterically crowded five-membered heterocyclic systems. Part 2. Conformation of 2,2,5,5-tetramethylpyrrolidin-3-ol from nuclear magnetic resonance spectroscopy, crystal structure, and molecular mechanics calculations

Sterically crowded five-membered heterocyclic systems. Part 2. Conformation of 2,2,5,5-tetramethylpyrrolidin-3-ol from nuclear magnetic resonance spectroscopy, crystal structure, and molecular mechanics calculations

Synthèse de composés cyclopentaniques chiraux, di, tri et tétrasubstitués. Application à la synthèse de dérivés Oxa‐13‐prostanoïques

A case of negative homoallylic coupling constants: 3‐cyclopentenone

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